PSU potential short

[Cubixic]

Today I made the really dumb decision of opening my PSU without waiting a reasonable amount of time before doing so. I had initially opened it because of a PSU fan being extremely loud and vibrating. After I thought I fixed the problem, I accidentally left the power cord plugged in while trying to put the metal case back on. While slipping it back on, I accidentally pressed the metal case against a component of the PSU which resulted in a large spark from inside the PSU. The part that it touched was the side of what looks to be a heatsink of the PSU. (I think this because it looks very similar to my CPU's heatsink.) My computer won't turn on now and I have no idea what to do.

Should I take it to a shop to see what's damaged and have them replace whatever's broken? How would I know if anything else is damaged as a result of this short? Would it be worth trying to figure out the issue on my own? I'm worried that I'm just going to mess something else up. I'll post a picture of my PSU here after making this post.

 

[CountMike]

I wouldn't use that PSU any more even if a repair is viable. Those heat sinks are part of the circuit for the transistors attached to them, that's why you got a spark.
For any future work on PSUs, disconnect from power and press start button for a few seconds before even opening it's case. There are some powerful capacitors in there that can stay charged for long time. Pushing start button and shorting input contacts with a screwdriver ensures all are drained properly.