The correct procedure is;
1 disconnect PSU and ups,if fitted.
2 remove mobo battery,the small circular one.
3 press and hold power button for a minimum of 15 secs.This action ensures the mobo capacitors are fully discharged,because their use is to temporarily store electricity,basically.
The mobo chip is then returned to factory setting and the bios back at default setting,ready for us to mess it up again.
PLEASE,NEVER short any battery.