Nexus 7
Android 4.2 JOP40C Jelly Bean update has been released for Nexus 7.

Google has released Android 4.2 (Jelly Bean; build JOP40C) as an Over the Air (OTA) update for its devices and the first updates went to Galaxy Nexus owners. Soon after, the files went to Nexus 7 owners.

Now, Nexus 7 users who upgraded their devices to Android 4.2 can root and install ClockWorkMod (CWM) Recovery, with this guide. IBTimes UK reminds its readers it will not be held liable for any damage to the device during installation and that this guide is meant only for the Nexus 7 running Android 4.2 (JOP40C).

Pre-Requisites

  • Download Nexus 7 USB drivers and enable USB debugging mode
  • Ensure all important data is backed-up
  • Ensure battery has at least 80 percent charge
  • Ensure bootloader is unlocked (check here for a guide)

To Root Nexus 7 on Android 4.2 JOP40C and Install CWM Recovery

  • Download Android SDK from the developers' site and install USB drivers (check here for a tutorial to set up Android SDK (Fastboot/ADB) on Windows)
  • Download Fastboot and extract in android-sdk-windowsplatform-tools directory
  • Download SuperSU v0.97 (CWM-SuperSU-v0.97.zip) and copy to SD card on Nexus 7
  • Switch tablet off
  • Download recovery-clockwork-touch-6.0.1.0-grouper.img and copy in android-sdk-windowsplatform-tools directory
  • Switch tablet in to Fastboot mode (to do so, press Volume Down and Power for a few seconds until text appears on screen; this is bootloader mode)
  • Browse to android-sdk-windowsplatform-tools directory and open Command Prompt (Shift + Right Click > Open Command Prompt)
  • Type - fastboot flash recovery recovery-clockwork-touch-6.0.1.0-grou and press Enter
  • Now, select Recovery from Fastboot menu and enter Recovery mode
  • Use Volume buttons to scroll to Flash Zip from SD Card and press Power to select
  • Now, select Choose Zip from SD Card and confirm with Power
  • Browse to CWM-SuperSU-v0.97.zip on device's SD card and select to confirm installation
  • After installation, return to main Recovery menu and select Reboot System Now (this may take a few minutes)

After device boots up successfully, the Nexus 7 should be rooted on Android 4.2 JOP40C (Jelly Bean) and also have custom CWM Recovery installed. This can be verified with the Superuser app or the Root Checker app.      

Head over to this thread to learn how to unroot Nexus 7 on Android 4.2.  

[Source: Team Android]