Apple TV won’t work

I can turn on my smart tv and the Apple receiver with the Apple TV Remote, but the Apple receiver won’t fully function. It only turns on and off. There’s no visuals after turning on. I’ve disconnected it many times for long periods of times, and I have checked all the cables and cords to make sure nothing is loose or damaged. Everything seems to be working, but I can’t see anything when turned on. What else could it be?