I believe the problem you may be having has to do with the “Scheduled power on/off” option. Which lets you schedule your phone to turn off and back on itself. Which you can specify the time and the frequency as well. You can also just use one and not the other (just turn your phone off or turn your phone on). You can set it Only Once, Monday to Friday, Everyday and Custom. To toggle off and on you access the feature first going into the “Settings” app, followed by the “Smart Assistance” and then going into the “Scheduled power on/off” menu at the very bottom. From there is should be easy to figure out if that was indeed the problem..