Chosen Solution
Last night my phone was charging and I was watching a movie on it. It was fine until I left the room for five minutes . When I came back, the phone was so hot it almost burned my hands and was turned off. I cooled it down but since then, I was not able to turn it back on. Official Apple support tried to fix it through iTunes but it doesn’t even recognizes my phone.
You would need to rule out parts by replacing the battery then dock connector. Although it sounds like it has developed a faulty charging circuit component on the logic board. If replacing the battery and dock connector doesn’t fix the issue it will have to be repaired by a reputable repairer. If you have a repairer in your town it wouldn’t hurt to get them to diagnose the problem before you spent money on parts.
