Although the Android 4.1.2 update started rolling out to the Nexus 7 two days ago, not everyone has gotten the OTA quite yet. For those not running the latest CM10 nightlies, waiting may have seemed like the only option. However, it turns out that updating the Nexus 7 to the latest Android build is actually quite easy, thanks to the fact that it is possible to download the official update file directly from Google.
If you are one of the few people who has a custom recovery and wants to switch back to the new stock build, then all you need to do is download this official update file and flash it through the custom recovery as you would any other ROM. Everything should work fine, although you will likely lose root access.
If you still have a stock Nexus 7, then the process is a bit more complicated but by no means terribly difficult. First, download the update file above, and the Android SDK if you don’t yet have ADB installed. If you need a bit of help getting started with ADB, then this older but still relevant guide might help. Once you have ADB installed and the update file on your computer, go ahead and rename the update .zip to jb.zip and move it to the ADB platform-tools directory to make running the commands easier.
Then, grab your Nexus 7 and power it down. When you power it up again, hold the volume down button to boot into fastboot. Once there, use the volume buttons to scroll through and select Recovery from the menu. Once you see a green Android with a red warning sign, press volume up and power simultaneously to pull up a menu. Select “apply update from adb” in the menu, and connect the Nexus 7 to your computer via USB. Now, one simple command will finish the update process. Simply type adb sideload jb.zip, wait for the process to complete, and reboot the Nexus 7.
As with any update process, everyone’s mileage may vary, but this is one of the easiest non-OTA installs that I have done. In all, it took me about five minutes total, and that includes installing some missing ADB libs. If it doesn’t work as well for you, feel free to ask any questions in the comments, and if it does enjoy the new features on your Nexus 7.