Original post by: pierrej ,
I would contact Apple Customer Relations and tell them that during the repair of the motherboard for the nVidia GPU issue, that the tech damaged the left IO board and they didn't replace it. As for if there is something that can be replaced or resoldered in place, i don't know the part enough to tell you. Somebody else here will be able to tell you exactly what part on the left IO board to look at. Personally, I would just replace the left IO board as you will at least know that it will work as you have already tested that way.