take a look at this teardown. . since we still do not have any clear identification on which IC has failed, you will have to take a close look at the logic board, identify the burned IC and replace it. The IC's are all SMD and thus you will need a hot air reflow, or reball depending on the IC, work station. Unless you have experience with this, I would suggest to get an old board and practice a lot, or to find someone to replace it for you.