More than likely its the Bluetooth/wi-fi board. I've run into this a couple of times with mine but it was just the ribbon cable going to it. I've had mine apart a couple of times (replaced the blue-ray drive) and also borrowed the Power supply for testing on another system. If your comfortable trying to fix it yourself take it apart and mess with the cable first. After that try replacing the board, not really sure if theres a good way to test the board itself. But the wi-fi issues your having also point to that one board.