I would guess you’re gonna have to reset it, but I’ve also never seen this. I wonder if you have erase after 10 failed passcode attempts turned on? I would turn that off. You’ll probably be fine resetting as I’m fairly certain it’ll restore all its data from backups it saves to your phone, but I could be wrong. You’ll definitely still have all your health and workouts data though.
Every time I’ve fallen (usually playing sports) it’s gone off. So I haven’t had it not go off when it should, but I have had it go off many times when it shouldn’t. I work in an auto shop, so I’m occasionally hitting things pretty hard. Goes off at least once a day at work, sometimes twice. I want to turn it off, but who knows, maybe it’ll actually come in handy some day