Chosen Solution
I bought an iPhone 6s off of a friend and it needed a new screen, I had another 6s that was in near mint condition but the board was iCloud locked so I did a board swap instead of just a screen replacement. When testing it afterwards, I constantly got the no signal message with or without a sim, at first I thought it was the baseband ic because when I dialled *#06# I got nothing but after a factory reset, I got a signal and the imei came up in the dialler. Great, I turned it off left it a bit and then when i turned it back on it was behaving the same as before but the imei and field test would come up in the dialler. I also noticed that it got really hot around the camera. Does anyone have any advice or know what could be causing the problem, currently I’m thinking that its the antenna so I might swap them as I have a whole phones worth of replacement parts. Thanks.
This sounds like a faulty Wi-Fi chip. It is a common problem on the 6s. I think you will find the heat is not coming from the camera but is coming from the Wi-Fi chip. Remember that these Wi-Fi chips on the 6s are binded to the NAND so if you replace the IC you will need to undind it.
