No matter what time of day I shut down my phone, it turns itself back on automatically at exactly 9:58 AM. The only way to keep the phone off is to remove the battery. There are situations where I must have the phone turned off, but I can't.
There are no timers set.
I have tried resetting everything to factory settings.
I had the phone exchanged but the new one has the same problem.
Has anyone else seen this problem and found a fix for it?
Have you tried to do a factory reset on the phone without entering any google account address? That way, you will make sure that the issue is not caused by an application that is installed in the phone. If it still doesn't work, you might have to contact the technical support so we can take a look at the situation with you.
The issue turned out to be caused by "Do Not Disturb" rules. Even though these rules cannot be set to directly power-on the phone, their mere presence causes the side effect of booting the phone once a day.
There are several pre-installed rules. After deleting all these rules the device now remains turned off indefinitely.
These rules are found under Settings -> Sound & notification -> Do Not Disturb -> Automatic rules.