My iPhone 11 Pro is flashing the apple logo on and off every 5 seconds or so and isn't responding to anything, what should I do?

The Apple logo appears as more or less the first stage of restarting the device. If it is appearing in a regular cycle that suggests the startup is unsuccessful for some reason, and it is making repeated attempts to start. This can be caused by a low battery without enough power to complete startup, so I suggest putting your phone to charge for several hours if necessary and see if that gets you past the problem.

If the problem persists after charging, try the Forced Reset procedure to be sure the software and processor/memory has been completely reset. Simply follow this sequence:

Short Press on Volume Up

Short Press on Volume Up

Press and hold the Side Button until the Apple logo appears (again!) then release and let it try to reboot.

If it still doesn't work you need hands-on help from Apple's support technicians. Contact Apple Support to arrange service.