Looking to restore your Galaxy Nexus to a pure stock ROM after installing a custom ROM or some other modification, or just looking to upgrade to an Android 4.1 ROM built from the latest Android sources? XDA Senior Member kalo86 has released a rooted version of the latest Android 4.1 build – JRO03L – which is completely stock except for root and has no other modifications, which you can flash to get back to a rooted stock Android 4.1 ROM.

Let’s take a look at how the JRO03L based Android 4.1 Jelly Bean ROM can be installed on the Galaxy Nexus.

Compatibility

This ROM and the guide below are compatible only and only with the international GSM Galaxy Nexus, model number i9250. It’s not compatible with Verizon/Sprint variants or any other device. Check your device model in Settings » About phone.

Warning!

The methods and procedures discussed here are considered risky and you should not attempt anything if you don’t know completely what it is. If any damage occurs to your device, we won’t be held liable.

How to Install AOSP JRO03L Android 4.1 ROM on the Galaxy Nexus

  1. This procedure will wipe all your apps, data and settings. Backup your Apps and important data — bookmarks, contacts, SMS, APNs (internet settings), etc. This Android backup guide would help you.
    NOTE: Don’t forget to at least note down your network’s APN settings, which are required to make mobile data work. Go into Settings » More » Mobile Networks, click on the APN that is in use, then note down the setting for each field. While APN settings should be automatically restored from network, you can enter them manually if needed to make mobile data work. You can also find your APN details → here.
  2. Unlock the bootloader on your Galaxy Nexus by following the guide → here. This will erase all your data, including the data on the SD card, so back everything up first (see step 1). Skip this step if your bootloader is already unlocked.
  3. [Important!] Install TWRP recovery on your Nexus by following the guide → here. Make sure to flash the GSM version of recovery. You need recovery to be able to install the ROM and can also use ClockworkMod recovery instead of TWRP. Skip this step if you already have TWRP or ClockworkMod recovery installed.
  4. Download the latest version of the ROM from here.
  5. Download the Google Apps package. This will install apps like Play Store, Gmail, etc. which are not present in the ROM by default.
    Download Gapps  |  Alternate Link  |  Filename: gapps-jb-20120726-signed.zip   
  6. Copy the two files downloaded in step 4 and 5 to the phone (DO NOT extract the files).
  7. Turn off the phone and boot into TWRP/CWM recovery. To do this, press and hold the Volume Up + Volume Down + Power buttons together till the screen turns on. Then, scroll to the Recovery mode option using the volume buttons, then select it using the Power button to restart in recovery.
  8. Now, tap on Backup, then slide the blue circle button at the bottom to the right to start backing up your current ROM, so that you can restore it later if something does not work out with the new ROM. After backup is complete, go back to the main menu by clicking the home button at the bottom left of the screen.
  9. Select Install, then browse and select the ROM file you downloaded in step 4 above. Confirm installation to flash it.
  10. After installation of ROM is complete, repeat step 10, but this time select the gapps-jb-20120726-signed.zip file to flash the Google apps package. Confirm again so that gapps are flashed.
  11. Select Wipe, then select Factory Reset and then confirm the data wipe. This will not wipe your internal SD card’s contents, so do not worry. Then, go back to the main menu by clicking the home button after wipe is complete.
  12. After wipe is complete, select the Reboot system button to reboot the phone and boot up into the ROM. First boot will take up to 5-7 minutes.
    NOTE: If you want to go back to your previous ROM, boot into recovery, select Restore, then restore your previous ROM by selecting it from the list.

The JRO03L based Jelly Bean Android 4.1 is now installed and running on your Galaxy Nexus. Visit the source page for more info and to get the latest updates on the ROM. Share your thoughts on the ROM in the comments.