@wangumwanza the only other obvious thing to try would be to replace the sub board (daughter board) and to check the ribbon cable going from the sub board to the main board. If after replacing those you still have the same issues, then you will be looking toward a board-level repair. [guide|98335]
If nothing else, take a look [https://www.youtube.com/watch?v=S-bskGFWhmA|on here] and see if that helps you after those two other things I would try first.