Hello,
It happened to me too 2 times, very frustating...
First failed: a double usb sqare not good cabling, ok for the first upper port connector, but the lower was inverted (check pin order in the manual or on the pcb and adjust the cables on the connector to match the MB.)...with the number of the impacted port seen on the boot screen (n°28 for me for the sqare, at the down of the MB)
Second failed: à screw was fallen sowewhere behind between the MB and the case, or just fallen under the rear pannel connector of the MB under the heatsink, don't know where exactly, but like you, have all disconnected from MB, with the error msg stay on the screen , impossible to desacivate them in bios before he automaticaly reboot within 15 secondes, cold sweats, fountain.
Clear CMOS 2 or 3 times in doubt, and it finaly boot...without error....ouf
Shaking the case was not enough, i had to unscrew the MB from the case to hear something hurting the case !! A screw !! From the top of the case when i was installing the WaterCooling...
Perhaps something similar for you, if enough time before reboot, try to desactivate the faulting port in bios identified on the boot screen in the error msg, or in last perhaps RMA if really no possiblities to restart.
