I got the screen replaced yesterday as it was badly smashed, and today when the phone went flat, it then went to the restart screen. The phone keeps blinking off and on every 30 seconds or so, but every time it's on, it's the white apple logo on a Blank black screen
Read more: https://iphoneus.org/faq/my-iphone-7-is-stuck-on-the-restart-screen-anyone-have.html