That could be caused by two things there besides a dead board. First is the supply good? If the supply is toast that will stall the works. The second and too often found to be the case is to check power connections and even try replugging the four wire 12v cpu feed. If there's a loose contact in that it will look like something is no good and no light will appear on a good working supply.
when unplugging and replugging that only press down very lightly until the retainer clicks and see how that goes. That's been seen when swapping out one supply for a larger model thinking the new supply was no good only to find that one contact was loosee inside the molex connector.