Chosen Solution

My computer just shut down and won’t power back on. Won’t do anything. It is like it isn’t even plugged in. I have tried a different power cord. I tried holding the power button. I have unplugged everything from the usb ports. I have opened up the computer - I am wondering where the diagnostic led lights are. I am wondering if it is the power supply board - it does look like some wiring melted - although its not black or burnt…

Be sure to discharge the big capacitors and handle it with one hand. I may be mistaken, but that looks like where the transformer bridges from the AC side to DC side. It will have very high voltage there. If that’s exposed wire in the pic then it is likely indicating a problem. The end of one wire looks yellowish too, as if it may have been hot. All of your symptoms point to a bad power supply. About 70% of the time I see these it’s the Power Supply, so I’d definitely put my money there.

The diagnostic lights are to the right of the RAM slots.

The diagnostic lights are under the RAM slots. See picture