Mac Pro 5,1 won't boot. No power, no noise at all, only a couple LEDs.
I have a customer's Mac Pro, mid 2012 machine which won't boot at all. When I press the power button, nothing happens at all, except a light odor of the magic smoke (from electronics, that is). The only time something noticeable happens is when you are looking at the logic board while plugging in the power cord. What I see are the top two LEDs that blink red momentarily in the upper left corner, below the #1 HDD. Those lights go out almost immediately and do not illuminate again when pressing the power button. I can get the lights to stay on if I depress the power button while plugging the machine in and hold the button in for about 7-10 seconds. They will stay on permanently after that.
When I press the Diag button near the LEDs, the 4th LED lights up amber, but nothing else notable happens. This also happens if I have the red lights switched on as I mentioned above. I tried the SMC button, but that didn't do anything either. Nothing at all in either case.
The customer already replaced the power supply, so I am wondering if the logic board is bad. I am going to get another power supply to be sure, but what else could it be??? Is there some other board I don't know about? Can someone help me interpret the LEDs?
Is this a good question?