I've revised all the posts of this thread to more accurately reflect what we know about the IMEI issue at this point. Development and hacking moves fast, and this is no different.
So, from what we've learned so far it appears the Galaxy SIII has a place where it is supposed to backup your IMEI and modem/NV data. This is in case that information was ever to get wiped from the EFS and other locations. However, for whatever reason that backup system does not work. Either the initial backup is corrupted, or it is storing empty information (thus the "0" in IMEI). For whatever reason, when the phone reboots, it may randomly get kicked into a cycle that causes the phone to restore this corrupted or empty backup, thus replacing the only GOOD copy (since the backup isn't working properly) with the bad copy.
With that being said, that appears to be as far as we know at this point. Now, good news, as much development has been made. You will want to do your backups in order here. Just do the fix and then the Synergy zip as well. The original QPST method is still down in post 3 if you want all the backups you can get
So, first backup:
1. Its time to fix Samsung's derp on the bad IMEI/NV data backup. This is extremely easy as the GSIII has a bootpoint to make this happen. It was discovered during the bootloader testing for the Verizon GSIII variant.
You can do it two ways, either in ADB or Terminal. In ADB:
adb reboot nvbackup
Your phone will reboot, you will see some blue text on the bootloader screen basically stating its backing up the info to the correct directories and giving you a proper backup, fixing the Samsung derp.
Now this *should* take care of the IMEI issue, as it appears we fixed what is causing it. That being said, we haven't gotten 100% confirmation yet, and so you would be well advised to be safer rather than sorrier, and follow on below with the backup steps outlined further.
DO NOT RUN THE BELOW COMMANDS UNLESS NECESSARY FOR RESTORE. IF YOU DO NOT RUN THE FIRST COMMANDS FIRST YOU WILL RESTORE THE SAMSUNG DERP IMEI AND FLASH YOURSELF TO "0"
If you do lose IMEI in future, you restore from backup using similar commands, either in adb:
adb reboot nvrestore
So, Second Backup (d2vzw only):
The next backup step was found by a Synergy developer, again from information uncovered during the bootloader information that was gained. To make it simple, it showed that IMEI and NV data was stored across various partitions, not just EFS, which is why the EFS fix was not working on the device. The following will backup all the applicable partitions the IMEI is spread across. It also includes a backup of the backup you just created (the backup partitions that Samsung had derped on). Cool huh? Its also super easy.
Download the .zip file from here:
Flash it in recovery of your choice (Clockwork/TWRP). It will create a folder on your sdcard/synergyrom/backup with a backup image. If you lose your IMEI in the future, and the nvrestore mentioned in Step 1 doesn't fix it (gets corrupted again, whatever) this should. Just flash the backup .zip in recovery again. Highly recommend you move it elsewhere after its flashed (Dropbox, PC, external SD... you know the deal).
These backups are looking pretty successful, and more so than the QPST method was, so that's why I'm recommending these first. The more backups the better though folks, until developers can get a better grasp on what exactly is causing these issues and how to fully stop them.
TrevE: Synergy/Flashable .zip
Edited by Goose306, 29 December 2012 - 01:52 PM.