Chosen Solution
I have an iPhone 4s that has been water damaged. The only issue is that it will not use the battery at all. While plugged in it turns on and shows 100%, it immediately shuts off when unplugged. Everything else works. I have disassembled the phone and cleaned all visible corrosion on the main board and flex connectors (there was very little corrosion near the power management unit, aka PMU). I have checked all visible solder joints with a microscope and all components appear to be fine, with the exception of one capacitor near the PMU. I have tried 3 different replacement batteries that were tested in other iPhones, the batteries are good, and charged to 4.0 Volts. I have also tried replacement charging ports, no change. I have tested all of the small components near the battery connector with a multimeter and they are also fine. The battery terminal solder joints are fine. When the battery is connected, the voltage across the board + and - terminals reads 0.0 Volts. I need help finding which components/chips might need to be reballed or replaced to fix this issue. What IC’s are related to this issue? I have searched for hours for a schematic or PCB photo to show which IC is the culprit, and came up empty handed.
Sounds like your logic board is at fault. I can guarantee you have a bad capacitor somewhere causing a short between the +/- at the battery connector. you can check this with a multimeter by connecting the first and last pin of the battery connector. If it has continuity then you have a short. You will have to take out the emi shields and find out exactly which capacitor is causing the problem. sometimes you can take out the circuitry from a battery and solder it to a dc outlet and find where it gets hot. Most of the time you can tell visually where the short is due to the corrosion
the battery is most likely bad. Same thing happened to me, took a battery from another 4s and that worked fine
MY samsung note 3 faced the same problem. I was using my phone and had 75 % battery on it. I went out for sometime and when i turned on my phone it did not turn on. I was shocked, i thought i’ve drained it to 0%. I went and put it in charge then i power on once. It came and showed it had 100%. I took out the charge seeing it had 100%. but then it turned off. i tried power on but that didn’t work it , i tried this again and again. then i removed the battery kept it aside for 5 minutes put it back and then!! It turned on. it was back in the 75% battery.
