E970 JB OTA Update - bibanon/android-development-codex GitHub Wiki
The Jelly Bean 4.1.2 OTA Update changes the partition scheme to more closely match the Nexus 4, allowing the use of modified Nexus 4 kernels, which is critical to any modding.
Method 1: Standard OTA Update
You can go to Settings->General->About Phone->Software Updates on your phone to request an OTA update from AT&T. If you don't get one, you have to wait 24 hours to try again.
Method 2: LGNPST
If you don't want to wait forever to download the OTA update, you have to use LGNPST to flash the OTA.
Install LGNPST
Pastebin - LGNPST Installation and Usage Guide
(if the above doesn't work, use the below)
Pastebin - Manual Install LGNPST
Send phone into Download Mode
Pastebin - Send phone into Download Mode
Install Stock Jellybean 4.1.2 OTA
XDA-Developers - 4.1.2 JB OTA Update LGNPST ZIP