That was my first thought since it matched the behavior.

I took the panel off, extracted the control board, and none of the buttons appeared to be stuck. This was bypassing the button “covers” and just using the PCB buttons on the board itself (basically just hooked the bare board back to the wiring harness to test.

What makes me feel like I wasted $80 is the control board looks pristine. No visual evidence of failure, no apparent moisture damage/corrosion, etc. Still hoping that’s where the problem is because I can’t return the replacement board (unless it’s defective itself) and I haven’t the foggiest idea of how to replace the main control board (assuming I can find one). Even then, that may not be the issue (could be a dodgy wire between the panel and the main board, for example).

From what I’ve read, even Samsung repair techs basically just throw parts at it until it’s fixed or they replace it under warranty or tell you you’re out of luck. (Mine’s out of warranty)

I’ve had it on a UPS for several months because of exactly that. My power’s pretty stable, but when it’s about to go out in a storm/winds, it goes full poltergeist for 2-3 seconds, flashes rapidly, and then either goes out completely or back to normal.

Granted, it raw-dogged power for its whole life until then, so it could have had accumulated damage.

Yep. Last summer was super dry (my poor lawn lol), and had way more yellow yackets than I can ever recall. If this summer is dry, too, hoping my preventative actions will help.