Shield Tablet Open Source Factory Preinstalled
This is compiled from Nvidia's source using instructions found on this page Link
You need to have an unlocked bootloader and adb/fastboot.
Be aware this does not include any of nvidia's apps or google's frameworks/play store and is just plain android with no extras. (If someone can pull from their /system it may be helpful). I will try to add more later, but this should at least get any bricked tablets going until nvidia released a factory image.
Run flash.bat while unlocked/ screen on(if your computer hasn't been approved for adb yet), or while in bootloader.
Or flash each file in fastboot, instructions are in the nvidia link if you need more.