This tutorial is for restoring your entire TV Shield in the event something unfortunate happens. In order for this to work, your TV Shield has to be able to boot up and display the Nvidia logo on screen. Otherwise, your TV Shield is bricked, and there is nothing you can do about it.
1. Unplug your power cable and connect a USB OTG cable to your computer.
Now, here is the tricky part that requires perfect timing.
2. Connect your power cable and almost immediately hold the power button for roughly 3 seconds.
** This may take multiple attempts to get the timing down. You may want to hold the power button for slightly longer than 3 seconds, ~3.1/3.2 seconds.
If successful, you should see the bootloader screen.
Tap the power button to navigate the menu and hold the power button to select.
3. Now go to the folder where you downloaded the files and type in the following commands:
./fastboot flash recovery recovery.img ./fastboot flash boot boot.img ./fastboot flash system system.img ./fastboot flash userdata userdata.img ./fastboot flash staging blob ./fastboot flash dtb
** Your device may or may not need to restart after each command, which means repeating the steps above. Also, you may not need to flash all of the above depending on what files are damaged.