I had never heard of this trick so I thought I’d pass it along as I just got it from Dell. This may be OEM, so it may apply to other hardware.
Turn on num, caps and scroll lock
Press ALT-E to erase the nvram
Press ALT-F to load factory defaults
Press ALT-B to reboot.
I did this through a KVMoIP so I wasn’t sure it was working until the ALT-B when the box did reset.