Chosen Solution
I got iPhone 4S, it was water damaged, I took it apart and cleaned it with Isopropyl, took apart the motherboard and cleaned it, and all connectors. I replace dock connector and battery. Now when I turn on the phone, it works but the motherboard gets really really hot, until I HAVE to shut it down. Battery stays cool. When I plug charger, it shows the little symbol of “charging” although the battery level keep going down and not up. Must be some component on the motherboard, right? Is it a hard fix?, does the phone even have a chance in this world? Thanks so much for any help.
There’s clearly a shunt somewhere drawing current. I would first check your reassembly to make sure all the parts got back together correctly. As I recall there’s a piece of insulating tape near the camera - make sure that’s in place. Another item to check is the connector to the display. Make sure it’s clean and properly seated. The backlight power feed goes through that connector and it’s one of the bigger power draws in the phone. Pull that connector and check with a magnifying glass for any possible shorts. Don’t scrub the surface of the board. There are some very small SMD parts on the board. You can scrub some of those right off the board if you’re not careful!
