Frozen on the white restarting screen

My iphone7 plus was glitching so I decided to shut it down to give it a break.

When I restarted it, it froze on the white screen with the apple. Its been like this for half an hour now, and I have tried restarting it and holding down other buttons while doing so.

Every now and then the white screen goes black, then back to the white starting screen.

Need help with how to fix this and turn my phone back on.