If you want to find out if your power supply is toasted, take it out of the case and unplug all the cables that connect it to your computer.

Connect it to a socket, than on the main 20 PIN cable (the one that goes into the motherboard) make a contact between one of the black cables (GND) and the green cable which is on the position 14 (PS_ON). (more info about this here)

If it starts the power supply is ok and the computer doesn't start either because of the motherboard or the CPU.

You might also want to read the MOBO manual and see if the pattern in which the led flashes is some kind of code that might indicate something else is wrong.

Best of luck.