Like Grobe said, power outage tends to take out multiple components, not just PSU, so you should actually get a spare PSU and start going through the normal diagnostic and test each component of the computer. In terms of fixing actual pc components, you need to have extensive knowledge on logic board repair and ect if your going to try to "fix" a component. Fixing a psu can be dangerous and not recommended as there are capacitors in there that have a high amount of electricity and can kill you. So again, if you find a component is damaged, replacing it is your safest option.