New and unpaired Apple Watch stuck on Apple logo loop - tried hard-resetting

Hey all.

I just bought a brand new Apple Watch 5 series today on a January sale. It started up normally in the beginning but when pairing it to my iPhone (12) I had to update to WatchOs 8 - which is fine. I tried updating 3 or 4 times but I always got the same message: update failed - an error occured. The last time I tried it got stuck on the Apple logo loop. I have tried the classic hard-restart many times without luck. Since I haven't been able to set the watch up completely, and it certainly isn't paired, I can't do the FindMy stuff either, or reset the watch to the factory settings via iPhone. I did also try the hard-reset side button thing but no factory reset option shows up.

What should I do?