Apple TV shows a black screen
I have an LG GX OLED TV connected to a Denon AVRS750H receiver through the eARC HDMI on the receiver. My son bought us an Apple TV 4K. I have it plugged in to power and the power light is on. I have a 4k HDMI cable connecting the Apple TV to one of the HDMI inputs on the back of the receiver. When I go to the LG dashboard on the tv one of the inputs shows up as Apple TV but when I click on that input I get a black screen, nothing is displayed, nothing happens.
I've looked at several YouTube videos and done several searches both here and on google but all of them assume that after plugging in power and cables you will automatically get a setup screen. But I see nothing. I really don't know where to go from here.