Made some progress. I was about ready to toss it in the trash, but decided to try a simple test - connect the Roku Ultra directly to one of my PC monitors. It took a while, but it eventually booted up and asked to go thru the setup process! Glad I gave it one last shot.
Now to integrate it back into my home theater system. The system is pretty simple, but I suspect that something else in it may have gotten reset or changed also (I do think the Roku had some issues as well). The cat does occasionally walk on the remotes, so who knows.