+ Remove the power supply
+ Remove the PC battery
+ Remove the CMOS battery
After removing all above items, wait for 10 sec, then install them back.
Start the PC, you will be noticed of PC configuration (F1 to skip or F2 to enter the setup page). You can go either way.
After everything is removed, press the power button "on" (it obviously will not turn on but will discharge the remaining current in the computer circuits and drain the cmos temp memory to reset it completely).