1. Install the latest android sdk from https://developer.android.com/studio/index.html#downloads
  2. Install the google usb driver from https://developer.android.com/studio/run/win-usb.html
  3. On your Nexus 7: enable developer settings by going to “Settings”, “About phone”, scrolling down to the “Build number” and tapping it 7 times. Next go to “Settings”, “Developer Options”, “USB debugging” and enable it.
  4. Connect your Nexus 7 to your PC and click “Ok” on the “Allow USB debugging?” prompt that pops up on your Nexus 7.
  5. Open a command prompt in the platform-tools directory of your android sdk. Type adb devices and you should see your Nexus 7 listed.
  6. Enter adb reboot bootloader to boot into the bootloader.
  7. Type fastboot oem unlock and press enter.
  8. A menu will popup on the Nexus 7 - select “yes” with the volume up/down and power buttons. On the bottom of the screen you should see lock state: unlocked!