Connectivity issues with Xbox one Controllers

Okay, so I have been trying to find information on this for a while and can’t seem to find anything. Although, I may just have poor “google-ing skills” lol.

I would like to buy a new Elite controller and really don’t want to shell out $150 for one. So I was thinking if I bought a broken one on Ebay, then I could fix it and use it. A lot of them have connectivity issues and I didn’t know if there was specific part in the controller that would be responsible for it. What I am trying to figure out is what part on the controller is responsible for wireless connectivity and Bluetooth(when compatible) Which board should I replace, if any? Do they sell just that part?

If someone can point me in the direction of schematics for the Elite and normal controllers that would probably be all I need, unless you have a much more simple idea. I’d rather not have to take apart one of my own controllers to figure it out.