Not an easy answer as the scenario doesn't fit any of the diagnostic troubleshooting scenarios.
One thing to check is peripheral devices. For example, take out the GPU. Does the T5500 power on? If not, I'd re-seat the GPU and attempt to power on. Still if no power, disconnect the HDD and see if the unit powers on. If it's neither of those two, though your motherboard has the amber light, the problem could lie within it and hopefully it's not dead. If it were one of the processors, you'd get the appropriate error code. Re-seating the CPU's, one at a time, is another way to troubleshoot.
HDD seems to be missing from the diagnostic list. May be you'll have some luck there.
If it were the RAM, an error code would show.
Nothing should look burnt or melted on your motherboard.
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