|It would be hard to determine exactly what component/s have been wiped in that rather unfortunate disaster lol|
But you could start with bench testing it, if you have extra parts, then try a new PSU first, test the mobo last as it involves the most pulling apart. If you have a cheap PSU with low amperage etc. then just remove your video cards.
If you know anybody that has a multimeter you can use this to read your motherboard voltages, but from experience, when computers go wrong in that sense, its usually the mobo, i've replaced 2 in the last 3 years because of short-outs.