Casio XJ-A130 Projector: A lot of dead pixels around the corners

COMPLETION ANSWER

This is a bad DMD. The part can be replaced, but it requires major disassembly of the unit and the part is not cheap. The issue with these is many happen years after they flood the used market, which drove the price of nice ones down by a ridiculous margin for a slightly worse model.

See this example on a dead Dell 1210s with the same failure:

I have been able to find the DMD for this one on eBay, but you need to search as such: "Casio XJ-A130 DMD". A lot of them are coming from China so if the chip is bad you're going to lose money by returning it, so consider it a crapshoot. However, if you can find a good one in the US for cheap it may be worth trying. However, if this is too old to even have HDMI I'd probably upgrade.

The issue is the TI-made DMDs have mirrors that move as they alter the "pixel". As the units age from hard use in the office before they land in our laps for 20-30% of the original price (less with a bad lamp) or even free (where we "recycle" them to being personal use projectors) can and DO fail with time as the spring assembly eventually breaks and it 'sticks" in that position. DLP units are very prone to this and it's not unheard of for people to dump them once it starts with 1 bad mirror. I will dump units for 1 dead mirror, or when I burn out the lamp (as I got it, or when I use up the lamp I bought if needed); it ALWAYS GETS worse.
This is one of the other major reasons I tend to (begrudgingly) relamp DLP's at times once it's over a certain age... This can occur at 500 hours on the lamp I put in a unit potentially sold 8 years ago that was only somewhat recently discontinued (e.g.: 2012 launch, 2017 discontinued), and I am locked into buying similar units until I exhaust it, and then once I exhaust the lamp I either have to junk the final unit OR relamp it and continue the cycle. Anything with KNOWN ISSUES like the 1210s get junked once the lamp I get drops dead for this reason.