About 5 years ago my wife and I purchased an Apple TV , (4th gen, model A 1625); it ended up getting put aside, and lost in the shuffle until this week the she found it. We have been attempting to set it up, but it has been unable to connect to Apple servers to activate; we have tried to connect with a device (iPad Pro, with working wifi connection, and manually. We thought maybe there was a problem on Apple's end, so we decided to try again the next day, but now we've tried everyday for 3 days without success. Tonight I decided to try and do a restore by connecting it to my Mac Book Pro (mid 2014 Retina 15 inch, w/ Big Sur), and it does show up, and the Mac Book offers to upgrade and restore it, but when I attempted to do so, after downloading the software, when it attempts to install, it stops and gives a message that says "The Apple TV “Apple TV” could not be restored because the firmware file was corrupt.". The Apple TV shows it is currently running tvOS 9.0. It is a 5 year old device, but was never taken out of the box until this week.
apple tv could not be restored firmware file is corrupt
SOLVED!! So I decided to try hooking the Apple TV to our other Mac, a 2020 iMac w/ 5k Retina display, also running Big Sur, and it was able to run the update/restore without a hitch, no complaints about firmware, so go figure. In any event, it's happily running tvOS 15, and working great!