Editing build.prop without causing bootloop - LG V30 Questions & Answers

I'm trying to modify my V30+ (bootloader unlocked, running US998 20a) so it "looks" like a Pixel 2 XL. The reason is so I can use the phone to activate a Google Fi sim card, and that can only be done from certain approved Google Fi phones.
I was using the method in this thread to accomplish this, but it causes a bootloop when I edit the build.prop. I tried editing using a root explorer and using a build.prop editor, but obviously I'm tripping dm_verity checking or something by modifying the system partition because when I reboot it just goes straight to fastboot. I have to flash from an external TWRP img to restore the original build.prop.
Is there any way to edit the build.prop so this won't happen? Would I have better luck trying to make my phone look like, say, a G7 or a V35?

Related

Is it possible to modify system files after flashing a firmware?

Hi, I have a rooted Lenovo B device (Mediatek M6735M) with TWRP recovery. I tried to change some build.prop values using an editor app but the result was I bricked my phone (and had to flash stock firmware again). Now, I wonder if and how I can apply some changes to the system files after flashing the firmware.
I want to ask you: is it possible to modify sys/system files after the firmware has been flashed (even the read-only ones), or is pre-flash manipulation the only solution? For example: is it safe to pull a system file with adb, modify it, then push it to the phone with adb?
Black Heretic said:
Hi, I have a rooted Lenovo B device (Mediatek M6735M) with TWRP recovery. I tried to change some build.prop values using an editor app but the result was I bricked my phone (and had to flash stock firmware again). Now, I wonder if and how I can apply some changes to the system files after flashing the firmware.
I want to ask you: is it possible to modify sys/system files after the firmware has been flashed (even the read-only ones), or is pre-flash manipulation the only solution? For example: is it safe to pull a system file with adb, modify it, then push it to the phone with adb?
Click to expand...
Click to collapse
No. You want to root your android again to do these.
Ashwinrg said:
No. You want to root your android again to do these.
Click to expand...
Click to collapse
I forgot to say that I rooted the phone again. I'd like to know if it is possible to edit system files after flashing a firmware (and rooting the phone) or if I'm forced to apply all system changes before flashing. Also, I'd like to know what kind of changes are allowed and/or forbidden (in order to avoid another brick).
For example, I found a read-only "serialno" file in "sys" folder and this file contains the serial number of the device. Could I pull this file with adb, change the content of this file (with another serial number) then push it into the phone?
Black Heretic said:
I forgot to say that I rooted the phone again. I'd like to know if it is possible to edit system files after flashing a firmware (and rooting the phone) or if I'm forced to apply all system changes before flashing. Also, I'd like to know what kind of changes are allowed and/or forbidden (in order to avoid another brick).
For example, I found a read-only "serialno" file in "sys" folder and this file contains the serial number of the device. Could I pull this file with adb, change this file (with another serial number) then push it into the phone?
Click to expand...
Click to collapse
You can change anything after rooting your phone. Make sure you are doing it correctly. Keep nandroid backup to recover from bad scenarios.
Ashwinrg said:
You can change anything after rooting your phone. Make sure you are doing it correctly. Keep nandroid backup to recover from bad scenarios.
Click to expand...
Click to collapse
Ok, but I'd like to have some general tips or advices before doing that. For example, I read (somewhere, here on xda) that file permissions have to be the same as the original file, so if I edit a read-only file I have to restore its read-only status or I could brick the phone. Is this true?
Black Heretic said:
Ok, but I'd like to have some general tips or advices before doing that. For example, I read (somewhere, here on xda) that file permissions have to be the same as the original file, so if I edit a read-only file I have to restore its read-only status or I could brick the phone. Is this true?
Click to expand...
Click to collapse
Yes. If you change permission to read-write then after modification you want change permission to read-only.
Grab ithat build.prop file and transfer to memory card using TWRP. Edit at PC and restore it

[MOD][9/10]Easy change CSC S8/S8+(possibly more) using root without wiping data

Hello,
I think I have found a method to change your CSC without wiping data on rooted samsung based roms, might be possible on completely stock rooted aswell.
I am not sure if this is needed, but I did flash HOME_CSC_OXM_G955FOXM6DSK9 as CSC in Odin before doing this. This does not wipe any data.
You should use your desired CSC firmware HOME_CSC for your device.
Steps:
1. Open some root capable text editor/file browser - I use Root Explorer
2. Edit /efs/imei/mps_code.dat
3. You should now see your current CSC Code
4. Edit it to whatever code you want your device to be. It needs to be 3 capital letters.
5. Save
6. Reboot and hope for the best
7. In my case it rebooted twice and then It loaded with the CSC I wanted it to be.
It also does switch from 4G icon to LTE/LTE+!
I have tested it on AlexisRom 8.3 available here:
https://forum.xda-developers.com/showpost.php?p=81247573&postcount=5132
It is stock based, so this method should work on stock Galaxy Pie roms aswell.
This ROM is OXM Multi CSC, but a lot of devices are multi csc aswell.
Of course I am not responsible for any bricked devices or any other damages, although I don't see why those could happen.
Please report back how it went for you!
This might also work on any recent Samsung rooted devices across various devices such as s10/note10. Please check it out and let everybody know!
Reserved
I think it might be possible for any stock based samsung devices that keep the CSC data this way.
Bumping as I need confirmation this works perfectly fine across different firmwares, so far nobody reported back whatsoever and I really want to move this into Samsung section, if it's confirmed working on stock roms aswell.
can you make it flashable to twrp for samsung s8 android 10?
Bang Onik said:
can you make it flashable to twrp for samsung s8 android 10?
Click to expand...
Click to collapse
Then I'd have to either create as many zips as there are CSCs or aroma installer.
Too much work, all you have to do is edit a single text file on your phone.
That's almost as easy as making a note in a notepad on your phone, but instead of notepad you use root capable file explorer.
If this gets more recognition and more feedback is provided, I could do it, but not until it's tested more widely and on more devices.
From my experience,
You could install your desired CSC by flashing csc_sec.zip within TWRP that you get from unsparsed cache.img firmware (lookup simg2img). Make sure to first mount the system partition and untick the "Unmount System before installing a ZIP" in the setting.
After that, you could change CSC by entering Preconfig Manufacturer-defined-MMI by entering *#272837883# in the dialer (Phone) app if it response to it. If there's no response then you need root access to bypass it. One app that's able to access it is PHONE INFO by vndnguyen. In the Other Tools Section, open CSC CHANGER and you'll have a choice to change your CSC.
But the cost of it, is that, you need to wipe your data. You'll also lose root access and have to reflash Magisk.
With this method, I've confirmed that it's working on Stock Samsung Galaxy Note 4 SM-N910C/H.
Edit in TWRP is recommended since you can also backup your EFS partition first. No need to root your phone if you want to, since you'll get root access in TWRP anyways.
1. Make sure to backup your EFS partition in TWRP before doing this.
2. Mount EFS partition
3. Advanced > FIle Manager > efs > imei > mps_code.dat > Edit File
4. Save it by Ctrl+O > Enter (Check Mark) > Ctrl+X to Exit
Note that this will only change your Original CSC Code. You will also need to edit your "/system/csc/sales_code.dat" if you want to change your Firmware and Active CSC.
But, I still don't have any idea of what are the consequences by not wiping.

[help]Editing boot.img results in bootloop[help]

I need help editing the default.prop of my rooted boot.img for an LG LM-X210ULM K8+. I want to mark ro.debuggable off as 1 instead of 0 but which i have no problem doing but when i use any kitchen program it puts it back together as 15mb instead of 32mb and when i flash it to my device it always bootloops.
If any one could help i would appreciate it. Im including a copy of the rooted boot.img freshly pulled ftom my device
The size probably isn't the issue. Using AIK the size was even bigger than the original.
It's all just 0x00 the rest of that partition...
By using my old uImage/_recovery unpack-repack batch file
http://cxzstuff.blogspot.com/2013/03/uimagerecovery-unpack-repack-batch-file.html
the result was smaller but still a bit bigger than the Magisk had made.
But that is irrelevant really... result attached.
Yea i dont get it. The size doesnt matter as long as it diesnt exceed the max amount of space the partition can hold. But why does changing one value cause the boot.img to boot loop after flashing.
Even the boot.img you made looped after flashing
Duhjoker said:
Even the boot.img you made looped after flashing
Click to expand...
Click to collapse
Just tells that it's not the tool used. Or mine oldie is as bad/good as the newer one in this case.
What that Magisk img had was like it had some signature but it should not be needed and probably just garbage left there from the stock...
Should not matter, but how about doing it other way around? Modify the stock boot first and then give it to Magisk for rooting.
I think it was stock. Ill have to make sure though. wonder why magisk doesnt make the image debuggable to begin with. But your right it might be that im using a magisk patched image. Ive got some firmware already broke down ill give it another try here in a bit and post my results.
Duhjoker said:
I think it was stock. Ill have to make sure though. wonder why magisk doesnt make the image debuggable to begin with. But your right it might be that im using a magisk patched image. Ive got some firmware already broke down ill give it another try here in a bit and post my results.
Click to expand...
Click to collapse
So here we are. There should be some shortcut or something left to the original sub forum at least for a week or two when you boys move these threads - dammit...
Any luck? You have a customized recovery? How about these?
https://forum.xda-developers.com/an...g/mod-bootimage-adb-unsecure-patcher-t3618558
Yes luck tonight i did a fresh reflashing on my QC Lg k8+ and decided to break open the boot.bin from the kdz i used and made my changes to default.prop then i put the renamed to boot.img on my phone and let magisk patch it then flashed it via fastboot and dared it to go into system. Then i double dared it. Then for safe measure i double dog dared it to boot into system to which it had no choice but to go along with the or be labled a @!%\**__(€.
It booted.
So the lesson learned is to patch a fresh boot.img with your default.prop changes then have magisk patch it for root.
Now oddly when i patched and tweaked my recovery using carlive kitchen, i also made sure that the same changes to default.prop or rather i made sure they had been made and they had. But any terminal like emulator or termux pulls up the props using getprop with the changes unmade and i still cannot change the values of the system build.prop and when i patch it manually it reverts on reboot.
I literally have to open a vi in twrp to make changes. And forget about copying my own patched build.prop to system in twrp. Because that leads to boot loop as well
Ok so is there a reason that you dont make those changes in the boot.img any more? Because the past two days i have woke up to no root. I have had to reflash my boot.img both times
Ok i just compiled my first kernel from lg source code and now i dont know which of the split images in my folder is the zimage
Back to the drawing board quite literally. Im stuck for sure.
I need to make edits to a few files like init.rc and init.lge.power.rc to allow for changes in my newly compiled kernels. Basically im adding a couple properties and some cpu frequency stuff. Plus i want to make it back to adoptable storage and add a second sd partition for ext4 projects im working that would work best right off the root file system.
Im using the stock extracted boot.img from a kdz using salt and carliv kitchen to unpack and repack i have also mkbootimg tools that i compiled myself and some static arm version.
I extracted the ramdisk place my new kernel image in and repack with the init files changed and flash using recovery or fastboot and bootloop every time. And magisk isnt signing with the verity key.
ok i dont know whst was going on the other day but i can split boot.img again and make changes with out looping.
i used gparted on my linux machine to partition my 128gb sd card with 3/4 vfat and 1/4 ext4 i know that by using adb it will automount but thats one timr and i may need to switch out every now and then plus it put a center part in it of about 15mb. with gparted i get the two parts with no bs. any way i created a script that mounts the second part and even symlinks some stuff. it works good but im having trouble getting init.rc to run it.
on early-init
chmod 0755 /system/etc/init/init.mntsd.sh
exec system system /system/bin/sh /system/etc/init.mntsd.sh
any tips

Can't seem to write to /system/vendor/etc

I guess I'm a moron and can't figure this out :v
Using stock rooted Oreo, Magisk, edXposed, everything that goes with them. TWRP 3.2.3-7.
Lately, I've been using my headphones while driving to work. I need a touch more volume over stock to deal with wind noise.
The problem is, I absolutely can't get /system/vendor/etc into a writable state.
Attempts to modify mixer_paths_tavil.xml whilst booted up fail, either resulting in an unreadable file (Total Commander) or just not working (Root Explorer).
Trying to flash a modified zip (just grabbed a dual-speaker mod and replaced the xml) in TWRP results in no file being created; it doesn't seem to throw an error, just silently fails.
Manually copying the xml to /system/vendor/etc using TWRP's file manager ~appears~ to work, but attempts to set permissions results in error code 1. The file doesn't exist upon reboot.
Remounting manually as RW in TWRP's terminal doesn't seem to help. And yes, "mount System as read-only" is unchecked.
I can make build.prop changes, so I know /system is writable. The only way I can get anything written to /system/vendor/etc is restoring a full system backup.
I've modified this file before; I manually tweaked the call volume higher and enabled "fake" high-impedance mode.
So I'm sure I'm doing something really stupid here. Help.
Septfox said:
I guess I'm a moron and can't figure this out :v
Using stock rooted Oreo, Magisk, edXposed, everything that goes with them. TWRP 3.2.3-7.
Lately, I've been using my headphones while driving to work. I need a touch more volume over stock to deal with wind noise.
The problem is, I absolutely can't get /system/vendor/etc into a writable state.
Attempts to modify mixer_paths_tavil.xml whilst booted up fail, either resulting in an unreadable file (Total Commander) or just not working (Root Explorer).
Trying to flash a modified zip (just grabbed a dual-speaker mod and replaced the xml) in TWRP results in no file being created; it doesn't seem to throw an error, just silently fails.
Manually copying the xml to /system/vendor/etc using TWRP's file manager ~appears~ to work, but attempts to set permissions results in error code 1. The file doesn't exist upon reboot.
Remounting manually as RW in TWRP's terminal doesn't seem to help. And yes, "mount System as read-only" is unchecked.
I can make build.prop changes, so I know /system is writable. The only way I can get anything written to /system/vendor/etc is restoring a full system backup.
I've modified this file before; I manually tweaked the call volume higher and enabled "fake" high-impedance mode.
So I'm sure I'm doing something really stupid here. Help.
Click to expand...
Click to collapse
Don't know, but tonight or tomorrow I'll shoot you a file to test.
ChazzMatt said:
Don't know, but tonight or tomorrow I'll shoot you a file to test.
Click to expand...
Click to collapse
Appreciated, but I think something's going pear-shaped and I just need to reflash the ROM; setting up for the drive home last night, it seems I've lost the ability to use direct output in Poweramp. I don't know how, since the system+system image backup I restored is known-good and audio is otherwise working.
Good ol' bitrot, I suppose.
Septfox said:
Appreciated, but I think something's going pear-shaped and I just need to reflash the ROM; setting up for the drive home last night, it seems I've lost the ability to use direct output in Poweramp. I don't know how, since the system+system image backup I restored is known-good and audio is otherwise working.
Good ol' bitrot, I suppose.
Click to expand...
Click to collapse
See my PM.

Access /system/ while in recovery to stop bootloop

Hello! I was editing the build.prop file on my Samsung S9+, and there must be a typo somewhere, because it went into a bootloop. I am able to boot into TWRP, so i was wondering if anyone has a method to possibly access /system/ while in recovery to undo what i did? I have a backup of the build.prop file.
If that isn't possible, would an Odin flash with HOME_CSC_*** fix it?
I would like to keep my data.
Thanks.

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