Did you have any success with this? I think mine is bad as well. Haven't found any bad parts yet though.

When I turn it on, no noise, lights, except the green led on the back. When I turn it off, after about 3-4 seconds, the blue LED on the front turns on for a sec or two, then turns off. One thing I did notice, is when turned on, I get a very faint clicking sound (or arcing sound?) coming from the supply board. Doesn't happen when the smaller of the connectors is connected to the green amplifier board.

Which parts did you find were bad? Were you getting 12V on the...

I got a GX280 off ebay a year or so ago.. From the symptoms, it sounded liks a PSU replacement but when I got it, it wasnt the problem.

When I try to turn on, it goes on for a few seconds, fan a full power, and then shuts off for a few seconds. Then it repeats it over and over. Sometimes it'll stop repeating and turn on, not POST, and just stay with on with the fan at full power. Typically after this happens and I turn it off, it will actually boot up.
I havent had it recently happen, but it has been known to shut off randomly (usually when its idle like overnight when...