Restore iPhone

My phone stopped working yesterday, and I'm getting the restore message but the fix for iPhone 8 or later isn't working for me. I press the volume up and volume down buttons, but when I press and hold down the side button no Apple logo comes on. The screen stays dark. When I release the side button, the Apple logo comes on the screen and the a flash comes shortly after and the logo disappears, and this continues to repeat with the Apple logo appearing and then a flash on the screen and the logo disappearing.