3 minute reset

I think, at this point, your best bet would be to make a Genius Bar appointment at your local Apple Store or Apple Authorized Service Provider to have them take a look and provide you with your options. Alternatively, you can use the "Get Support" link in the upper right-hand side of this forum's web page to get started.

Ref: Genius Bar Reservation and Apple Support Options - Apple

... and what have you tried, so far yourself, to resolve this issue so that we don't offer potential solutions that may not have already worked for you?

Did you happen to update the phone's iOS firmware before this issue started?