Here is a Picture of your Phone Internals, It has a black cable on the right side, that is your cellular antenna, you can replace it easy that cable. I have been dealing with new techs, and in that situation you have to options, order a new one or use one from another phone and adapt it.
Another case can be a damaged connection from the motherboard, and it is tha same case, you can solder a new one or you can adapt one.
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