while the relays are running, the 5v that powers them stays steady. i'm guessing I shorted something that overvolted or reverse polarized them. ground and 12v were both exposed, so shorting that could have given them -7V.
I try not to leave things exposed like that when working. I tricked myself by thinking it was okay to leave ground exposed, then working on 12V leaving it briefly exposed, while it was powered. two mistakes at once.
