06-12-2019 05:32 AM
I had the same problem. I bought a brand new Hero 7 Black and within a week the unit refused to switch on. The only way to switch it on was first to remove and replace the battery. This happened several times within a couple of weeks, so I reported it. "Technical" support were clueless and ended up exchanging my unit for another one, but the replacement unit behaved in exactly the same way.
I eventually noticed that the problem seemed to be linked to using QuikCapture. After I had recorded a couple of clips with QuikCapture activated (i.e. one button recording) the unit refused to switch on again until I had removed the battery and replaced it. I have switched off QuikCapture now and have not had the problem occur since (for several months now).
There is clearly an issue in the camera's firmware that no amount of unit swapping or resetting will solve. Hopefully someone at GoPro will look into this more carefully and fix it in a future version of the firmware.