Chosen Solution
I have shot many hours of video with this excellent (and underrated) device. Last week the on/off switch stoppled working. The batteries are good. I was able to back up all the video files to my laptop. Any ideas about the switch? It appears physically in excellent condition.
Switch could be bad or poorly connected to the board in a hard to see place or the board could be failing . I have an old Flip with a crack in the lens, otherwise works great that I would be happy to give you for parts if you decide you want to tear into it and try to get it going again.