iPhone won’t start

If your iPhone is an iPhone X or newer try holding the volume down and the lock buttons down until the apple logo appears than continue holding until after the apple logo disappears. If your phone is the iPhone 8 or older hold the lock button until the apple logo appears and continue holding until the logo disappears.

This could take 30 seconds or longer.

There should now be a different screen on your iPhone. Follow the instructions on it to try to update or erase your iPhone.

If this doesn't work I would recommend contacting apple support (Get Support) and notifying them of the issue.

It may be time to make an appointment at the nearest Apple Store for an evaluation and explanation of your options...

Apple Store - Find a Store - Apple