*Note: This is only for the GSM Galaxy Nexus.
Step 1: Download and flash ClockworkMod Recovery by heading over to this link.
Step 2: Download the Jelly Bean image, the root fix and radio from this thread over to XDA. Place all the downloaded files in the root directory of your Galaxy Nexus.
Step 3: Power off your device and turn it back on while holding down the Volume Down and Power buttons and you’ll boot directly into ClockworkMod Recovery.
Step 4: Take a nandroid backup of your device.
Step 5: From the main menu of CWM, wipe your data, do a factory reset and wipe Dalvik cache.
Step 6: Now select install zip from sdcard > choose zip from sdcard > select the Jelly Bean zip you downloaded and placed in your sdcard in Step 2.
Step 7: Now repeat Step 6, but this time flash the radio file.
Step 8: Again, repeat Step 6 and this time flash the root fix. Note: This step is not necessary if you are not looking forward to remain rooted after the update.
Step 9: Once you’re done flashing the three files, simply select reboot system now from CWM’s main screen and you’ll boot right into Android 4.1 Jelly Bean on your GSM Galaxy Nexus.
