[HELP] Stock ROM. Want to OTA but gpt.bin is a version ahead of everything else.

[Okahuma]

Long story short, didn't backup before everything, hard bricked with an OTA, recovered only by blankflashing and flashing the feb2018 gpt.bin (NPJS25.93-14-15) and then since I don't have the ROM for NPJS25.93-14-15, I flashed everything else from NPJS25.93-14-13.

Phone is working. Got TWRP in there, made a backup this time. Installing Magisk softbricks it, but that I'm trying to solve in another thread. Got the backup before trying to install Magisk anyways so I don't make it harder on myself to OTA.

I'd like to be able to do OTA updates, mainly due to the KRACK vulnerability that was solved with NPJS25.93-14-15.

The issue is: how do I get the phone back to the same version on everything? Afaik, I can't downgrade the gpt.bin to NPJS25.93-14-13 (when I try, I get the security downgrade error leading to a remote failure), which means I would have to bring everything to NPJS25.93-14-15 straight up? Can I do that without hardbricking again? As in, flash back the recovery from NPJS25.93-14-13 (the only thing that is not stock is twrp) and straight up do the update ignoring the fact that my gpt.bin is already from the version I will be updating to?

TL, DR Can a phone with NPJS25.93-14-15 gpt.bin and everything else NPJS25.93-14-13 make the OTA update to NPJS25.93-14-15? Can one downgrade gpt.bin somehow?

 

[segra246x]

Did you find a solution for your problem? Maybe it's possible to flash all patched files manually to bring all to NPJS25.93-14-15??

 

[echo92]

1)If you revert back to NPJS25.93-14-13 fully, you should be okay to use the OTA update to NPJS25.93-14-15. This only will work as NPJS25.93-14-13 is the firmware directly preceding the Feb 2018 update. Using a firmware older than this may well cause a hard brick when you try to OTA update. However, you must fully re-flash or revert to a completely clean stock firmware build - no TWRP, no root etc. Unlocked bootloader does not matter. Easiest way would be to fastboot flash the stock NPJS25.93-14-13 ROM

2)Yeah, generally you cannot downgrade GPT or bootloaders - this is the underlying cause of bricks, as flashing old firmware results in applying old OTA updates, which corrupt your bootloader. However, in this case you're applying an OTA update that is as newer or newer than your existing system, so you should be okay.

3) You could in theory flash the Feb 2018 stock ROM - this is not been fully verified but some users have been able to successfully flash it. Verify this first before flashing: https://forum.xda-developers.com/showpost.php?p=75961872&postcount=716

4)Rooting on stock Nougat on our devices requires a custom kernel. Attempts to root on the stock Motorola Nougat kernel appears to trip anti-rooting protections and so causes the boot failures you've mentioned. You'll have to flash the stock firmware, apply the update, then flash/boot TWRP, then flash ElementalX (or another custom kernel) then magisk.

 

[Okahuma]

Holy cow @echo92, thanks so much for the detailed answer! I'll give this a try and update here with results.