In my case the unit was working fine one day, the next day it would hang on the "Gigabyte Ultradurable" BIOS splash screen.
Chances are you have a broken USB device plugged in. The BIOS attempts to enumerate the bus, gets an error code, and just sort of stops there. Why there is no error message is beyond me.
It seems to continuously retry, since if you unplug the offending USB device, it will continue as if nothing had ever happened. You don't even need to reboot. So, start unplugging USB devices one by one until it magically restarts, and you've found the culprit. In my case it was a bad receiver for a Mele air mouse.
50/50 chance that Windows complained at least once about the offending device when you first installed it. So start with the one that originally gave you driver errors just a short while ago.