Earlier today, Google started rolling out the Android 4.2 Jelly Bean OTA update for the Galaxy Nexus and the Nexus 7. The update, however, is only being rolled out for the Play Store variant of the Galaxy Nexus — known as takju. Thankfully, an XDA developer — bigxie — has released a rooted Android 4.2 Jelly Bean ROM for the Galaxy Nexus that will work on any variant of the Galaxy Nexus.
So, if you own a Galaxy Nexus and cannot wait for the official Android 4.2 OTA update to be available, here is how you can manually install the update on your handset.
The steps below will work on any GSM variant of the Galaxy Nexus, including yakju and takju. It will, however, not work on the CDMA/Verizon’s Galaxy Nexus.
Before you proceed further, please make a backup of all the data on your phone including your pictures and other files on the internal memory of the Galaxy Nexus. Also, the steps below require root access with a custom recovery installed.
Step 1: Head over to this thread on XDA forums to download the stock, rooted Android 4.2 flashable zip file. Once the download is complete, transfer the file to your phone’s internal memory
Step 2: If you are already running Android 4.1.2 Jelly Bean on your Galaxy Nexus with a custom recovery, simply boot into CWM or TWRP, and flash this zip file. Your data and installed apps will remain intact in this case.
Step 2: If you are running any Android 4.1.x or Android 4.0.x based custom ROM, then you need to do a factory reset prior to flashing the Android 4.2 custom ROM.
If you are not sure how to flash or install a custom ROM, please refer to this guide.