@Tomlink Hello Dear same issue i have found in my Apple TV 4K. I am open it and soldering cables and make USB cable. it's need ipsw file. Previously i have crashed my Apple TV 4K then i am doing same process and using checkra1n tool so my apple tv 4k is start again normally. But now my iOS version is 15.1.1 and unfortunately checkra1n not support this version.