Try a hard reset. Hold the power and home screen button down until the apple logo appears and then let go. This will reboot the phone essentially. Hope this helps. Good day.
Which iPhone is it? Is it up to date on iOS 10.3.3? What happens when you try a hard reset? Does the Apple logo show at all? How long did you hold the buttons when attempting the Hard Reset?
On iPhone 7 you hold power and volume down. Not home button.
That’s on earlier iPhone models.
Please try to hold volume down together with power button until screen go black and still hold and when the Apple logo comes you release them.
Sorry. Didn't realize this was for iPhone 7. Like said above it's the power and volume down to complete a hard reset for the iPhone 7 series of phones. Big thx to above poster for pointing this out!!!