How To Manually Flash / Install Android 4.2 Jelly Bean On Galaxy Nexus & Nexus 7

It should also be noted that this method is applicable only to the GSM version of Google Galaxy Nexus (Takju builds), and all version of Google Nexus 7.

• CWM Flashable ZIP for Android 4.2 (Download for Galaxy Nexus GSM here, and Nexus 7 here)
• ClockworkMod Recovery installed (you can do that using ROM Manager)
• Patience & bravery

Step 1: Download the flashable OTA Update ZIP for your device from the links provided above.
Step 2: Transfer the ZIP to the root of your device’s internal memory.
Step 3: Reboot your device to ClockworkMod recovery (or any other custom recovery). If you are running stock recovery, you can always use ROM Manager to flash CWM, but we advise against that if you’re inexperienced there – better wait out a couple of days for OTA to become available.
Step 4: Perform Wipe Data/Factory Reset, Wipe Cache, and go to Advanced to Wipe Dalvik Cache.
Step 5: Hit back, navigate to “install zip from SD card”, and choose the OTA update package from internal memory.
Step 6: Let the update flash, and reboot system once that is complete.