Hello Dear
If you have some technical experience about soldering work then please open your apple tv 4k and target to hidden debugging port. Its back side of Ethernet port in this port 6 number pin is mode selection pin if you give 1V-1.8V max then apple tv 4k going in reset factory settings. I think its work for your apple tv. i am mentioned details about debugging port. https://www.theiphonewiki.com/wiki/J105aAP