Computer doesn't start after overclock?

If your running at 2.8 chances are the processor is just in a powered down state to save energy when not in use. And you dont remove the battery, look for the CMOS jumper, and a 20% OC is assanine to start with, Avoid the BIOS of you dont understand it. Its more than possible you fried you PC. Reset the jumpers wait 30 seconds then put them back to default and try again, if not you prob ****** up bad