If a phone isn't at a condition to allow them to assess a phone under the 24 month Manufacturers Warranty then they would insist on bringing the phone up to that standard before they will help.
They would be concerned that the accidental damage could be linked to the current issue and that this " chip " may grow if they disassembled the phone to repair it @Sean183
Samsung will have offered to repair the phone for a fee I assume.
In regards to the restarts try Safe Mode > Safe Mode > https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ turns off downloaded apps and themes etc which may highlight an app or theme that's causing conflict.
If that does not help then factory reset the phone again but don't set the phone back up using your created Back up just incase something in it is causing the conflict.
Set it up as a new phone instead.
Don't use any downloaded themes or wallpapers etc.
If it still continues then send feedback via your Samsung Members App.
Maybe a next software update will help !
Daily Driver > Samsung Galaxy s²⁵ Ultra 512Gb ~ Titanium Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
