Chosen Solution
I replaced the shell and screen on this iPhone X, as the whole phone was just cracked glass everywhere. In the past, when I just replaced the screen, everything worked as it should. The moment I replaced the shell, the phone has weak signals. The GPS gives a location around a mile radius, then freezes, bluetooth connects when very close to the device then disconnects randomly, WiFi connects when very close to the router, then disconnects, and the LTE stays connected but has very low signal and occasionally disconnects. I got the shell off of FixEZ, and it was one with the little parts already installed. I do know, during the process of fixing it, I did lose a little piece of metal shaped like a ring with a little line coming out. It was like a washer and it was in the top left corner if I remember correctly. Not sure if that has anything to do with it, but it’s a guess. Also I tried to check the bluetooth antenna that is near the taptic engine and it did look like it could get loose easily as well as I might’ve put the wrong screws to hold the plates that go on top of it. Not sure what it is so any help would be amazing! Thanks!
You should of binned the ‘little parts’ that came with the new chassis and done a total transfer of all parts. If you still have the old chassis I’d swap the genuine parts over then try it. These aftermarket shells can be garbage. Especially if they didn’t cost much.