[Q]Unlock VZW bootloader? Hard brick the Z2 - what would it take? - Xperia Z2 Tablet Q&A, Help & Troubleshooting

I'm pondering options with the vzw z2 tablet (sgp561) and before I start playing with this fire, I am curious what it would take to hard brick this so I know what NOT to try.
Any thoughts?

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In theory as long as fastboot works it should be pretty tough to brick. I don't really know how fastboot works on Sony devices I have mostly Samsung devices but I assume download mode work largely the same as fastboot. I have brought back Samsung devices from being very near full hard brick. That said they were old and had unlocked bootloaders. I am not sure how relevant my two cents is but that is what I have. On another note I also have the 561 and am more than happy to help in any way I can. I really want some CM12 on this thing since VZW probably won't give it to us until everyone else has had it for 6 months.

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Maxim512 said:
In theory as long as fastboot works it should be pretty tough to brick. I don't really know how fastboot works on Sony devices I have mostly Samsung devices but I assume download mode work largely the same as fastboot. I have brought back Samsung devices from being very near full hard brick. That said they were old and had unlocked bootloaders. I am not sure how relevant my two cents is but that is what I have. On another note I also have the 561 and am more than happy to help in any way I can. I really want some CM12 on this thing since VZW probably won't give it to us until everyone else has had it for 6 months.
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Well, I can throw a couple of "kopeka's" (cents) in as well.
Fastboot is a life savior. Bar none. With it, you can wipe partitions and flash new partition images. Now this is taken that the fastboot capabilities in the given bootloader are "full" and not neutered in some way. Yes, it could possibly be so.
The only way I know, where you can perma-brick the device, is by flashing things on incorrect partition formats, or flashing a bootloader not meant for the device.
Incorrect custom recoveries are notorious for this, as they flash incorrect partition info. (been there, did that).
Also, nand memory can fail after some flashings. It happens. No rhyme or reason to it, it just does. Generally it gets corrupt to the point wipes and formats don't clean it.

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Moscow Desire said:
Well, I can throw a couple of "kopeka's" (cents) in as well.
Fastboot is a life savior. Bar none. With it, you can wipe partitions and flash new partition images. Now this is taken that the fastboot capabilities in the given bootloader are "full" and not neutered in some way. Yes, it could possibly be so.
The only way I know, where you can perma-brick the device, is by flashing things on incorrect partition formats, or flashing a bootloader not meant for the device.
Incorrect custom recoveries are notorious for this, as they flash incorrect partition info. (been there, did that).
Also, nand memory can fail after some flashings. It happens. No rhyme or reason to it, it just does. Generally it gets corrupt to the point wipes and formats don't clean it.
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Click to collapse
In random readings, I've seen that "Unlock bootloader allowed=no" on some devices blocks fastboot. I can boot into fastboot mode, but I haven't tried flashing anything since I am not experienced in fastboot flashing. I think the easy test would be to read a partition in fastboot, then write it back. Do you know the commands to do so?

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da_reeseboy said:
In random readings, I've seen that "Unlock bootloader allowed=no" on some devices blocks fastboot. I can boot into fastboot mode, but I haven't tried flashing anything since I am not experienced in fastboot flashing. I think the easy test would be to read a partition in fastboot, then write it back. Do you know the commands to do so?
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You are correct. Some variants (Verizon for example), you can't unlock the bootloader. No unlock, no "full" fastboot or fastboot at all.
Although my original bootlocker was "unlockable" due to it turning out to be a "Demo" unit, I managed to flash an RU ftf, and got the unlocked bootloader. But it seems "some" carrier models don't allow for this. (as a sidenote, I've just reflashed my DRM keys back today, and now on a stock locked .167 build again. Just wanted to try it and see if it worked.)
Here's a list of useful commands (thanks to AndroidForums), but you can certainly find a ton by Google-it.
Code:
fastboot
usage: fastboot [ <option> ] <command>
commands:
update <filename> reflash device from update.zip
flashall flash boot + recovery + system
flash <partition> [ <filename> ] write a file to a flash partition
erase <partition> erase a flash partition
format <partition> format a flash partition
getvar <variable> display a bootloader variable
boot <kernel> [ <ramdisk> ] download and boot kernel
flash:raw boot <kernel> [ <ramdisk> ] create bootimage and flash it
devices list all connected devices
continue continue with autoboot
reboot reboot device normally
reboot-bootloader reboot device into bootloader
help show this help message
options:
-w erase userdata and cache (and format
if supported by partition type)
-u do not first erase partition before
formatting
-s <specific device> specify device serial number
or path to device port
-l with "devices", lists device paths
-p <product> specify product name
-c <cmdline> override kernel commandline
-i <vendor id> specify a custom USB vendor id
-b <base_addr> specify a custom kernel base address
-n <page size> specify the nand page size. default:
2048
-S <size>[K|M|G] automatically sparse files greater th
an
size. 0 to disable
A very useful thing to use, is for example;
fastboot boot boot.img
or
fastboot boot recovery.img
This is useful as it doesn't actually "write" the image to the device, but rather boots it in memory.
Usually how we test things such as new custom recoveries, boot.images and such.

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Moscow Desire said:
You are correct. Some variants (Verizon for example), you can't unlock the bootloader. No unlock, no "full" fastboot or fastboot at all.
Although my original bootlocker was "unlockable" due to it turning out to be a "Demo" unit, I managed to flash an RU ftf, and got the unlocked bootloader. But it seems "some" carrier models don't allow for this. (as a sidenote, I've just reflashed my DRM keys back today, and now on a stock locked .167 build again. Just wanted to try it and see if it worked.)
Here's a list of useful commands (thanks to AndroidForums), but you can certainly find a ton by Google-it.
Code:
fastboot
usage: fastboot [ <option> ] <command>
commands:
update <filename> reflash device from update.zip
flashall flash boot + recovery + system
flash <partition> [ <filename> ] write a file to a flash partition
erase <partition> erase a flash partition
format <partition> format a flash partition
getvar <variable> display a bootloader variable
boot <kernel> [ <ramdisk> ] download and boot kernel
flash:raw boot <kernel> [ <ramdisk> ] create bootimage and flash it
devices list all connected devices
continue continue with autoboot
reboot reboot device normally
reboot-bootloader reboot device into bootloader
help show this help message
options:
-w erase userdata and cache (and format
if supported by partition type)
-u do not first erase partition before
formatting
-s <specific device> specify device serial number
or path to device port
-l with "devices", lists device paths
-p <product> specify product name
-c <cmdline> override kernel commandline
-i <vendor id> specify a custom USB vendor id
-b <base_addr> specify a custom kernel base address
-n <page size> specify the nand page size. default:
2048
-S <size>[K|M|G] automatically sparse files greater th
an
size. 0 to disable
A very useful thing to use, is for example;
fastboot boot boot.img
or
fastboot boot recovery.img
This is useful as it doesn't actually "write" the image to the device, but rather boots it in memory.
Usually how we test things such as new custom recoveries, boot.images and such.
Click to expand...
Click to collapse
Well I was going to give it a shot but I turned my tablet off to reboot without making any changes to it and now it won't turn back on. I haven't had time to RMA it yet. It did this before but it just started working again for no reason. It is probably a good thing since it sounds like I probably would have bricked it trying anyway.

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Maxim512 said:
Well I was going to give it a shot but I turned my tablet off to reboot without making any changes to it and now it won't turn back on. I haven't had time to RMA it yet. It did this before but it just started working again for no reason. It is probably a good thing since it sounds like I probably would have bricked it trying anyway.
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Wow, talk about "timing". Luckily you didn't make any changes. Had a similar issue with mine last night (coming out of fastboot coincidently).
Did a fastboot boot to TWRP, and when it went to reboot, I had to mess with the Vol + and - nd PWR combinations a few times before it would boot.

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Do not play with verizon z2
I work with custom roms and such... I also have a Sony Z2 late tab... I built a rom for this device.... Never got to test it. Got two on it with no issues. And this is a pain as well due to anytime you use twrp you must reflash twrp or your in for a world of hurt. Well during my process twrp froze while wiping the system... I could get to fastboot but any command I tried to run It told me that it was locked and I couldn't use the command as I didn't have the rights. So long story short I wouldn't play with it till someone gets a unlock for it