If it was out of warrenty I'm suprised that they even stocked the mobo. At work every time I call emachine to see about replacing a mobo they are out of stock and are unsure about when they will be stocked again.
That's how they sell them so cheap. They sell junk mobo's and stop stocking...
You could check in device manager and see if it's still listed in there. If it's not or it has an exlamation point it's damaged or the drivers arnt right. It was probably fried when the power went out though.