This just recently started happening on my hero 4 silver... When I turn it on, sometimes it lets me scroll through the menus for a bit and then freezes, and other times it freezes right off the bat on the home screen. Also doesn't let me take photos or start recording. I was able to update the firmware, and I got in and was able to reset the camera, but it's still freezing with and without the memory card in the camera. Also, I know I have the correct microsd card, so that isn't an issue. Anyone experience this problem?