If your ATV isn't directly connnected to your receiver (like HDMI switch, HDMI to Toslink, etc.) then temporarily make an HDMI direct connection from ATV to Receiver. After set up you should be able to change back.
I was very dubious of this advice, but I tried it, and it worked!
Connecting the output of the AppleTV into my receiver and then from my receiver into the TV made it work, no training required.
Thanks very much.