PowerEdge T20 won't power up, power button & fans repeatedly turn on/off forever

1 year old. Press the power button, power button lights up amber, then white, CPU fan spins up briefly, then a beep and the power button turns off and the fan shuts down. Three seconds later the cycle repeats forever until I depress the power button for 5 seconds.

Is this a bad power supply? A bad motherboard?