I found this in another ifixit thread and it only seems to have been mentioned here briefly and I think most people would have missed it. There is a small antenna glued around the side of the headphone port, you should have transferred this to your new part as it doesn't usually come with it. When you put the screw back in the bottom left corner, you need to make sure the metal bracket is underneath the plastic you are putting the screw through, not on top of it. I had to do some serious digging to find that answer when I needed it. Unfortunately now my problem cant be fixed by that. Maybe its a logic board problem for me this time.