Problems with Roku

I have a Roku SD, connected via HDMI to AVR in the basement system.  I don't use it often but it has always worked fine.  Recently, I tried to watch via Roku and got only a green screen.  Plugged the Roku directly, via HDMI, into the TV and it worked fine.  Unplugged everything and then plugged Roku back into the AVR, got the Roku screen advisement that it was booting up, then it went green.  Tried other inputs on the AVR with the same result.  Tried other HDMI cables, no change.  It appears the green screen is generated by the Roku (not the TV), and since it showed the boot screen initially, it appears that the Roku signal is going to AVR (and TV).  Roku customer service has not been helpful ("try unplugging the Roku and plugging it back in").  Any thoughts?
Have you tried to reboot the AVR?  Unplug it, start pressing buttons at random on the front of unit to discharge any remaining capacitance, wait a few hours or even overnight and plug it back in.

Seems to be a disconnect between the HDMI input to the HDMI output on the AVR. It’s not passing the signal correctly.
Good suggestion.  I'll give it a try.  Thanks.