Download the Stock OTA Update 4.1.2 I747UCDMG2 from here:
Warning: This will update your bootloader, so proceed at your own risk!!!This means that your device should not be rooted or installed with custom ROM for it will possibly brick your device. You should also need to back-up all of your important files stored from the phone's memory, such as contacts, emails, SMS, photos, videos, apps and etc.
The update will also wipe data!
Attached is the 4.1.2 OTA update courtesy of icedmayhem!If you are rooted or runs with custom ROM, you should first roll back to stock official 4.1.1 firmware, grab the 4.1.1 UCDLK3 build here and then just follow the procedure on how to Odin back to stock.
This is what I did to update.
1) Odin back to stock.
2) Download update.zip, check MD5, then copy to external sd card.
3) Reboot recovery, install update from sd card, flash (update installs and phone reboots).
4) Use Odin to install CF Auto-Root.
5) Download Goo Manager and install TWRP or ROM Manager to install CWM
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