Today I tried out an old M2 for the first time with an USB/P2 adapter. For the first 10 minutes it worked fine. Then I set it aside on my desk, left the room for a second, came back and suddenly the caps lock and scroll lock lamps were on and not a single key reacts anymore. Nothing has fallen onto the keyboard and the keys are not stuck. I already replugged the board and restarted the computer, and the two lamps went back on immediately.
I run Fedora Linux on a mid-2011 Mac mini and would be thankful for any advice.