Lenovo Tab M8 (FHD) (TB-8705F): How to root? - Android Q&A, Help & Troubleshooting

Hello Everyone,
I am using my Lenovo Tab M8 (FHD) (TB-8705F) as a monitor to control a Mavic 2 Pro drone.
When connected to the controller unit it drains the inbuilt battery of the controller, which significantly decreases operation time. I enabled developer options and under "Default USB Configuration" I selected "File Transfer". However, each time the DJI GO4 app is launched this setting is over-ridden and it starts charging the tablet.
There are a few apps available that can turn off charging if the device is rooted.
I searched all over the internet and could not find a way to root my Lenovo Tab M8 (FHD) (TB-8705F).
Please suggest any links on how to go about this process.
Some of the processes I found need the stock-ROM, but no-one has uploaded a stock-ROM yet anywhere.
So I looked at how I can make a stock-ROM. To use those method I have tried to use MediaTek SP Flash Tool (ver 5.1944.10).
Still NO-GO. It does not support MediaTek Helio P22T Tab Octa-core 2.3G platforms yet.
Now I am in a bind. Please suggest an alternative way to root this device.
Some additional details of this tablet:
Lenovo Tab M8 (FHD) (TB-8705F)
Android Version: 9
Build Number: TB-8705F_S100058_191112_BMP
Kernel Version: 4.9.117+ #2 Wed Nov 13 05:11:41 CST 2019
Hardware Version: Lenovo TB-8705F
Software Version: TB-8705F_RF01_191112
Custom Built Version: alps-mp-p0.mp1-V5.140
RAM: 3.00 GB
ROM: 32.00 GB
CPU: MediaTek Helio P22T Tab Octa-core 2.3G
Display: 1920x1200
Camera: Front 5MP/Rear 13MP
Thanks in Advance.

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My bootloader is unlocked.
and I have tried these methods without much success, any suggestions on how I can make a ROM backup?
I tried these two tutorials to take a ROM backup, however, without much success.
https://android.stackexchange.com/q...nd-full-rom-without-root-for-mediatek-devices
https://forum.hovatek.com/thread-21970.html
The first issue I noticed with Wwr_MTK (I downloaded the latest version I could find: WwR_2.51_Eng) is that it did not have a drop-down option for the Mediatek MT6762.
It had options for MT6761 & 6763, but not for 6762. So it did not have a pre-configured scatter file format to choose from. So I used the option-2 and modified the Template.ini file to include it into the drop down menu options.
The second issue I came across was that Smart Phone Flash Tool (I downloaded the latest version I could find: SP_Flash_Tool_v5.1944) did not support MT6762 either. It has support for MT6761, though.
So I am not able to use SP Flash Tool to make a backup for the stock firmware.
Any suggestions on how to get past this roadblock?

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You can try downloading the full firmware using the Lenovo Moto Smart Assistant.

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Yaryk777 said:
You can try downloading the full firmware using the Lenovo Moto Smart Assistant.
Click to expand...
Click to collapse
https://forum.xda-developers.com/attachment.php?attachmentid=5001289&stc=1&d=1587547098
I just tried that. Problem is that the M8 (FHD) TB-8705F isnt available to choose in the list of devices. On ROMDevelopers there is mirror of {Mod edit: Link removed - Oswald Boelcke, Moderator} available which I'm unable to download because I have no membership. Maybe some can upload the file somewhere else. Guessing from the filename the URL on the official lenovo server should be https://rsdsecure-cloud.motorola.com/download/TB-8705F_USR_S100058_1911122350_V5.140_BMP_ROW.zip but since I have no download permission which is only granted through Lenovo Moto Smart Assistant I cant download it either. This is such a ****show

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la_tristesse said:
https://forum.xda-developers.com/attachment.php?attachmentid=5001289&stc=1&d=1587547098
I just tried that. Problem is that the M8 (FHD) TB-8705F isnt available to choose in the list of devices. On ROMDevelopers there is mirror of ... available which I'm unable to download because I have no membership. Maybe some can upload the file somewhere else. Guessing from the filename the URL on the official lenovo server should be https://rsdsecure-cloud.motorola.com/download/TB-8705F_USR_S100058_1911122350_V5.140_BMP_ROW.zip but since I have no download permission which is only granted through Lenovo Moto Smart Assistant I cant download it either. This is such a ****show
Click to expand...
Click to collapse
Found this randomly, not sure if it's legit:
https://support.halabtech.com/index.php?a=downloads&b=folder&id=69457
Edit nvm doesn't work

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i need the same
hi dear.
did you get any chance to root it.
please help i need to root the same device

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Yaryk777 said:
You can try downloading the full firmware using the Lenovo Moto Smart Assistant.
Click to expand...
Click to collapse
Please excuse the late reply to this thread. I was "locked-away" from my desktop computer as I had traveled out of state and a country wide lockdown was imposed here in India, right after I left--which was close to two and a half months--we were not allowed to travel beyond our neighbourhoods on most occasions, forget between cities in the same state, or even between states. It was a heavy handed lock-down of the entire country. I had left the tablet back at my hometown, so I could not pursue rooting it further for this duration. Just got back two days back and am going through the replies.
Yaryk777 is correct. I just checked (and downloaded) the stock firmware available through Lenovo Moto Smart Assistant (LMSA), which I did.
Not sure how to go about rooting the device from here, if anyone can suggest how to root a Mediatek device when a stock firmware is available I would really appreciate it. I had links to a few methods, but have forgotten them now since I have been away. I tried the two methods mentioned in my earlier post, and both did not work.
TWRP does not have a supported recovery for this device.
Any suggestions how to go about it?

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Ashok.Vardhan said:
Any suggestions how to go about it?
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Click to collapse
You need to copy boot.img into your tablet and patch it with magisk. Then flash patched boot file. That's all

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How do you do that?
Yaryk777 said:
You need to copy boot.img into your tablet and patch it with magisk. Then flash patched boot file. That's all
Click to expand...
Click to collapse
How do you flash the patched boot file then?

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I bought the same tablet to replace the 2013 nexus 7 I have running in my honda fit. For the lenovo to work I need the tablet to support otg charging. On the nexus 7 I installed timur's kernel to make that work. On this as far as I can tell, I need to update a flag in the kernel per these docs, https://android.googlesource.com/ke...-marshmallow-dr/Documentation/usb/msm_otg.txt (search for ID_C in the ACA section). Any help would be appreciated on accomplishing that.
Thanks,
Peter

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Ashok.Vardhan said:
Yaryk777 is correct. I just checked (and downloaded) the stock firmware available through Lenovo Moto Smart Assistant (LMSA), which I did.
Click to expand...
Click to collapse
What were the steps you used to get the firmware?

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PyroMike said:
How do you flash the patched boot file then?
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Click to collapse
Flash it with fastboot from your PC..
I did it and my device is now rooted.
---------- Post added at 12:28 PM ---------- Previous post was at 12:27 PM ----------
Isrgish said:
What were the steps you used to get the firmware?
Click to expand...
Click to collapse
To answer my question you can download thru the program "Rescue and Smart Assistant" from Lenovo on the rescue tab.

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Isrgish said:
Flash it with fastboot from your PC..
I did it and my device is now rooted.
---------- Post added at 12:28 PM ---------- Previous post was at 12:27 PM ----------
Click to expand...
Click to collapse
I tried to root it, but it couldn't detect my device when I was in Fastboot mode. Can you tell me how you did it?

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PyroMike said:
I tried to root it, but it couldn't detect my device when I was in Fastboot mode. Can you tell me how you did it?
Click to expand...
Click to collapse
Do you have the firmware?

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Isrgish said:
Do you have the firmware?
Click to expand...
Click to collapse
I downloaded it through Rescue and Smart Assistant.

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PyroMike said:
I downloaded it through Rescue and Smart Assistant.
Click to expand...
Click to collapse
Now to root.
1. Install Magisk Manager on your device.
2. Copy the boot.img file (this is in the firmware) to your internal storage.
3. Run Magisk Manager and select Install. Then select patch file.
4. copy this patched file to your PC and flash to your device.
That's all there is too it.

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Isrgish said:
Now to root.
1. Install Magisk Manager on your device.
2. Copy the boot.img file (this is in the firmware) to your internal storage.
3. Run Magisk Manager and select Install. Then select patch file.
4. copy this patched file to your PC and flash to your device.
That's all there is too it.
Click to expand...
Click to collapse
The issue that I am having, is that my device isn't detected while it is in Fastboot mode.

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PyroMike said:
The issue that I am having, is that my device isn't detected while it is in Fastboot mode.
Click to expand...
Click to collapse
In Device Manager do you see an item that has a yellow triangle (Check this while you are in fastboot)?
How do you get to fastboot?

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Isrgish said:
In Device Manager do you see an item that has a yellow triangle (Check this while you are in fastboot)?
How do you get to fastboot?
Click to expand...
Click to collapse
I open up PowerShell and use "adb reboot bootloader" to enter fastboot. When I type in "fastboot device" to check and see if the tablet is there, it just says "<waiting for device>".

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PyroMike said:
I open up PowerShell and use "adb reboot bootloader" to enter fastboot. When I type in "fastboot device" to check and see if the tablet is there, it just says "<waiting for device>".
Click to expand...
Click to collapse
Are on Microsoft Windows?