It is possible that there has been a power surge and it has affected your motherboard, however any time that I have see this the motherboard is totally unresponsive. You did say that you had motherboard lights on.
Do the obvious things like checking all your leads , make sure everything is plugged into your motherboard.
Can you access the BIOS, if so it could mean that you hard drive has died or it is no longer detected by the system.