I was able to find a consistent pattern, if that helps. If I turn it on, then switch it back off and back on after a moment, it loses audio and video and makes a sort of whining noise before it comes back on fully.
https://www.youtube.com/watch?v=ilmJ...ature=youtu.be
I'm going to try running it with the back off again, if only because the intermittent nature may mean the normal behavior when the back was off was coincidental.
This is definitely a signal problem, though. I'm just not sure how to proceed.