That's a crappy job from Apple. So I took the device to an authorized repair center, and they said: "that's a problem, and we can't repair it or even try different solutions of what you already did," sorry, buy a new one.
The second time that happened to me, with different models. Apple TV it's a costly disposable device.
Great job Apple
Apple TV 4K, tvOS 14
With a continuous flashing status light, the system software may need to be re-installed, externally through a computer. Unfortunately, for the 4K models, users can’t do this themselves. Instead contact Apple Support for restoring service.
With a continuous flashing status light, the system software may need to be re-installed, externally through a computer. Unfortunately, for the 4K models, users can’t do this themselves. Instead contact Apple Support for restoring service.
Apple TV 4K Rapid flashing white light
