Triangle of death - anything I can do?

Hi!

While scrolling through widgets watch resets.
This happens sometimes and I didn't mind, until this morning.
Now my 965 is in triangle of death mode, restarting all the time, just triangle is shown and then off.
Takes an hour now already.
Holding power/light button to shut it down doesn't work.
Connecting to PC doesn't change anything too, device not detected.

Is there anything I can do?

Best

Oliver