How to restore the Apple TV 4K, all suggestions are for anything but the 4K

Restore your Apple TV - Apple Support

If you have an Apple TV 4K

If you see a warning symbol  while trying to update the software on your Apple TV, or see a black screen on your TV and flashing indicator light on the front of your Apple TV, contact Apple Support. 

For the 4K model, you will need the assistance from Apple, if you can’t access the menus to restore on-device.

+1, you have to take it to your local Apple Authorized Service Provider to have it serviced.