I absolutely agree that engaging with these people beyond "we added checks to ensure your board has the RAM it came with, and this one failed" is a waste of time, but I think that at least providing that level of response would be much more aligned with the image they're still trying to project than just stonewalling entirely.

"We bricked your board on purpose even though it actually might work fine" isn't good image either. Like, they know they are doing a bad thing!

Very fair point.