Chosen Solution
I have just took my phone apart and turned it on and felt where the one spot of incredible heating is taking place, It’s in the mess of display cables. I was curious about what this means for replacement parts, What part should I replace? My display, battery, Cables?
When the iPhone 6s or 6s plus starts overheating and the heat is coming from the top of the board it usually means the Wi-Fi chip is has a short inside it. The Wi-Fi might still work for now but it will not be long before the phone will be inoperative due to overheating. The Wi-Fi chip is located on the underside of the board under the display connectors. I would suggest an upgrade as the repair would be more expensive than the phone is worth as replacing the chip is not straight forward and you also need to unbind the Mac Address from the NAND for the new chip to work.
