Computer wont stop rebooting

[Chodam]

My friend was messing around in my BIOS just messing around seeing if he could over clock my CPU. During that process he saved and exited out of the BIOS and now my computer keeps turning on and off. I thought it was a Power problem so I took out my graphics card and yet it still keeps restarting over and over so I can not get into my BIOS to change what he did. Is there anything that you know so I can fix this problem?

 

[Tmagic650]

There is a small round silver battery on the motherboard. Unplug the computer and carefully remove the battery. Wait a few minutes and reinstall the battery. Boot the computer