Got an Optiplex 7050 SFF used. When I plugged in the computer for the first time, I heard what sounded like all internal fans spinning at max speed for a moment and then shut off. I also smelled that classic burnt electronics smell (and immediately unplugged it from the wall).

I have been unable to get any sign of life from it since. When plugging in the power cord, the green power supply light on the back illuminates and stays on (I can tell that the power supply fan is running). Pressing the power button does nothing (no fan activity, no diagnostic or power button LEDs at all). I have tried unplugging everything (including internal components) with no change. Unplugged the power supply from wall, held power button for 30 seconds, plugged it back in and no change.

Any ideas?