Galaxy S8 - No cellular signal

"I solved this problem on my S8 Plus.

After changing the screen the network was no longer working, then I tried to press the lower part of the phone (near the home button) and the 4g network started working, I disassembled the phone, on the second board(the smaller one) there are some pins, which touch the plastic shell, with tweezers I lifted them ( a little bit ?) to make better electrical contact, I cleaned them with acetone and a piece of paper.  then I reassembled the phone and it is now working perfectly! These pins touch some metal pieces in the plastic shell, to boost the antenna signal i tink."

defective charge port if the cables are fully connection try a new charge port also reconnect the antenna connections just in case

"I have tried all the solutions did not work for me

Then I took the phone apart and looked In side

on further investigation I found a loose flex cable on the mother board where the main antenna connects by the charging port on the left

This Straight away fixed my gps location problem."

"I think the obvious thing is to disassemble the device and put back together methodically ensuring that all connectors and antennas are replaced properly and that the antennas are connect to the correct points on the board and not swapped over.

Factory reset the device, update the software and test again.

If none of that works I would assume that there is some damage to the bottom board and would swap that out. Once swapped out I would software the device again and then test.

If all of that fails it really needs to go to a professional who may diagnose a PCB fault."

I got a similar problem I swapped everything including the connection cable, speaker and the USB c port and I still can only get edge connection after a screen swap