This might be the problem. If you can take the bottom cover off your MacBook Air, there is a small sized board to the right of the laptop when you are looking at the bottom with the cover off. There are 2 wires connecting it to the logic board. One on top which is called a ribbon, and one below it. Take one side of the ribbon of of the board and lift it up so you can see the other wires. Check if there is damage to the wires and or if it's un plugged. I hope this helps!