My ROG phone II would randomly restart while i was watching some youtube videos.
Eventually it got on the Crashdump mode screen. It stayed that way and nothing happened. Eventually I was able to restart my phone, now it can't boot properly. If I'm lucky it will get to the lock screen and when I try to get in it will freeze and restart again, and again till it just turn off completely.
@Vegeta Based on your description, it is possible that there is a hardware malfunction with your device, and we recommend sending it in for diagnostics and repair. Since your phone is likely out of warranty, there will be a diagnostic fee and a charge for any necessary parts. The following is the contact information: https://www.asus.com/support/service-center-location