When my watch is on the charger, if I try to turn it on it goes into a sort of diagnostic mode, with screen test patterns and raw sensor readouts. Off the charger, when I try to turn it on I just briefly see the green triangle, then it goes away and there's nothing.
Watch was working fine until about a week ago, when it died immediately when I started record an activity (it made it through the activity selection and "wait for GPS" screens, then died as soon as I pushed the button to start recording). After that, it would turn back on a few more times, but would repeatedly die as soon as I tried to record an activity.
I saw a suggestion in another thread to "Delete Data and Reset Settings" from the watch menu, so I did that. It came back up and would briefly interact with my phone, but still died when I would try to record an activity. A couple of days later it wouldn't turn on at all.
I don't think there's been any issue with shocks, high temps, water, etc; the activity I was trying to record initially was just a normal morning run. Not sure what else I can try or if it's something I can have fixed.