Inferior PSU have little or no 'voltage/current regulation' to protect them from defective 'loads'....... like your computer system. Your system was probably drawing excessive current for your PSU and your PSU died.
I would dis-connect everything except the motherboard, CPU and fans; no drives,Ram, or video cards.
If it still fails... then you know its the mobo or Cpu. I would then take out the Cpu , to further isolate the problem. You may be able to have the Cpu tested at your local computer shop.
* other parts may also be 'toast', but you can check them later.
** power supply link......... may help you.