Originally Posted by garyd9
Yes, it's possible.
I guess you want some details, huh?
You'll need to get a Developer Edition stock recovery and a Developer Edition nandroid backup. (I'm lazy, so will just use "DevEd" instead of Developer edition.)
To get BOTH of these things, hop on over to a thread in the non-carrier specific M8 section: http://forum.xda-developers.com/show....php?t=2701376
Find and download the nandroid (TWRP) for CID BS_US002. Specifically, you should get the 1.12.1540.17 version. (There's a good reason for getting the older version...) You should also get a current TWRP image. (.img, not a zip file.) If you don't know how to get this image, then I'd advise NOT converting your device.
Then you can follow these steps:
Boot your phone normally.
Unpack the TWRP nandroid and place the folder into the proper directory on your phone's sdcard (/sdcard/TWRP/Backups/SERIAL_NUMBER/ or /sdcard2/TWRP/Backups/SERIAL_NUMBER) Replace "SERIAL_NUMBER" with your device's serial number. You should end up with a folder structure similar to: "./TWRP/Backups/HTXXXXXXXX/BackupName/" with the actual backup files in that directory.
... at this point, you might want to go ahead and boot into TWRP recovery to make sure that the backup you put in there is visible. It's fairly common for people to put the nandroid in the wrong place. I even did that myself once....
reboot into fastboot mode.
change CID to BS_US002 (BS_US001 is the "unlocked" version, BS_US002 is the DevEd version): fastboot oem writecid BS_US002
If you're starting with an AT&T branded device, there's no need to change the model ID (MID) as it's identical to the DevEd device.
reboot back into fastboot (to make sure the CID change worked): fastboot reboot-bootloader
use fastboot to put the proper DevEd STOCK recovery in place: fastboot flash stock_recovery.img
Probably not needed, but while in fastboot go ahead and run this: fastboot erase cache
Use fastboot to boot into (but not flash) the appropriate custom recovery. Example: fastboot boot openrecovery-twrp-22.214.171.124-m8.img
Use the custom recovery to wipe the data/cache/dalvik cache partitions.
Use the custom recovery to do a full restore from the backup copied to the phone above.
Reboot to the normal system. You can now accept OTA's and they should work. (They did for me.)
.... The reason for installing the older firmware version was to "test" the system by allowing the OTA to happen. If the OTA fails, then you screwed up the above steps.
Thanks. Can you provide more detail on how to accomplish this or refer me to a thread that has that info?
I was typing.