Replacing the battery on the iPhone 4S requires minimal disassembly. If your battery is swollen, [[What to do with a swollen battery|take appropriate precautions|new_window=true]]. [ … ] guide, calibrate [https://www.ifixit.com/Wiki/Battery_Calibration|calibrate] your newly installed battery: Charge it to 100% and keep charging it for at least two more hours. Then use your iPhone until it shuts off due to low battery. Finally, charge it uninterrupted to 100%. [ … ] [video|https://www.youtube.com/watch?v=i196dj1cZls]