A sort of BIOS corruption must've taken place, somehow; hence, I'd recommend clearing the CMOS:
Reminder: Please, ensure you wear an anti-ESD bracelet on an anti-ESD surface.
Unplug the power cord, remove all non-basic components; remove the RTC (Real Time Clock) battery and leave it out for 20 minutes. After this period of time, insert the battery back in, connect the power cord back in, and attempt to turn the system on; then, do the following:
1. Once in the BIOS setup utility, press <F9> to restore BIOS default settings.
2. Reset any customized BIOS settings.
3. Clear all DMI event logs by setting the option to "Enable", which is located in the Advanced/Event Log Configuration section of the BIOS Setup utility.
4. Finally, press <F10> to save the new settings and reboot the system.
I tried clearing the CMOS already some five times, and at least once the battery was out overnight. Didn't work, nothing changed.
After booting up, it still doesn't recognize any usb keyboard or mouse.
So it's impossible to even enter BIOS setup, because I can't press any keys!
I'm waiting for an aswer from intel if I can RMA this thing..
If you've tried with different keyboard and mouse at no avail, then, I'd recommend contacting Intel for case# documentation and consequent follow-up (if it's RMA, then, proceed accordingly):