Well, I read it yesterday, dithered, and did not respond. Here's what would have been.

I was given a Plus that had no video a couple of years ago. It turned out that the brightness knob had been turned way down. I know it sounds trivial, but the guy who did the giving actually knew his way around technology, yet missed the blindingly obvious.

It's most likely the components in your case, given how it started, but before you go gutting the thing, make sure you've twiddled your knob.