Have you cleared the CMOS?
If you clear the CMOS and it still happens, take the mobo out of the case, place on a non-conductive surface, un attach everything except 1 stick of ram, cpu heatsink and it's fan and the video card.
Try getting it to POST, if its out of the case and the CMOS was cleared and it still won't post, than the motherboard may be dead and you won't know unless you either try a different mobo or RMA this one.