Fajitas

Hello, I'm trying to resurrect my old Promedia ultra 5.1 speaker system. I plugged it in one day and turned it on only to hear a loud pop along with a burning electronics smell and the amp stopped working. I opened it up and noticed that there is a big standing transistor or something in between the large 820uf capacitors on the Indigo PDC board that looks like it is fried. The legs are burned up and the side of one of the adjacent capacitors is scorched. Anyone have any advice on what I can do to fix this, or what I can measure to figure out which components need to be replaced? Thanks for reading, Fajitas