I wanted to change the battery of my iPhone 6s, because it was dying. Today I did it. It took quite a long time. First I had to take out the old battery, but while doing that, I accidentally broke a cable, which caused the volume up / down keys to stop working. I had to buy a new cable on Ebay, so I could replace it. When it arrived, I installed it. But to do so, I had to disassemble the whole iPhone. After I reassembled it and installed the battery, I turned it on and know it works perfectly.