Supermicro PDSME+ not doing POST

[starless]

Hi, yesterday one of my servers (5 years old) died and did not boot anymore.

The motherboard is a Supermicro PDSME+.
When I connect the power cord, the power LED turns on green, and another unkown LED turns on orange (it is placed just between the South Bridge and the IDE connector, it's larger than others, but there is no mention of it in the manual!).
When I turn the system on, the two POST LEDs (green and yellow) turn on, but then they remain on, they do not blink or turn off, ever. As if the system was stuck at the beginning of POST. And the unknown LED becomes red; a pity I'm not able to know what it means; it might even be normal behaviour, I never opened that server before.

So, nothing else happens. No beeps, no other LEDs, nothing appears on the monitor.
Also all fans (case, system, CPU) remain turned off (except for the ones inside the power supply).

I tried removing everything from the system: HDs, controllers, RAM, CPU, fans, but even when CPU, RAM and everything else was missing, the motherboard behaved the same, no signals at all, not even a beep.

Is it really dead? All of a sudden?

I would have pointed at the power supply instead, but the server has three redundant power modules, so I cannot believe the fault is in the power section.

Thanks for any clues and hints about the mistery LED, too...

 

[starless]

Just for the record, I asked directly to Supermicro support, and they replied a few hours later confirming that the red LED indicates a motherboard failure, and the board must be replaced.