This very thing has been happening to my 950XL. It started by chronically force closing on my photos app, upon taking pics, and some apps. Force rebooting was occurring also. Then is started saying my SD card was corrupt and wanted to fix it. The "fix" didn't work so I removed the sd card. Over the next two days it kind of behaved, only force closing a couple times and force shut down once. Then just an hour ago it force shut down while it was on the charger and wouldn't boot up for several minutes. Trying all the key combos to get it to boot up wouldn't work. At best it would just vibrate every 4 or 5 seconds. Finally it booted up. I'm resetting it now.