Chosen Solution
My phone is overheating even on the lock screen, just after few minutes of using it makes it hot and displays the overheat warning. I tried doing a factory reset. the camera and flash works, the wifi on my phone is bugging i think it sometimes connect but sometimes wont. (ive just had screen replacement) it was not done by me. The wifi is totally fine checked it a couple times its just the overheat warning turns off the wifi and i was sometimes far from the router.
This is a common problem for the 6s plus. The Wi-Fi chip develops a short. I would make sure you have backed your data up. The replacement of the iPhone 6s Wi-Fi chip would cost more than another good second hand one.
