As some of you may know by now, Android 4.1.2 is currently rolling out to select Nexus 7 devices. So far we have found that it adds Landscape mode, a new bootloader that will allow you to boot into recovery from bootloader mode, and other performance enhancements. If you are running a custom Rom or any firmware other than bonestock then you know the process to receiving an OTA is a tedious one. There are a few ways that you can update your device to 4.1.2.
First Way- If you are running bonestock you can wait until you get the popup window shown above asking if you would like to install the available update.
Second Way- You can return to stock using a tool like Nexus7 toolkit, then manually flash this file in custom recovery
Third Way- You can return to Stock JR0O3D and follow a lengthy ADB manual install guide like this one
EASIEST WAY- You can simply flash the STOCK ROOTED OTA file found here via custom recovery over ANY custom rom or firmware! (be sure to WIPE DATA!)
So there you have it. Let me know how you came out!