5 - 30 Minuten
Battery was still sort of OK but I thought I'd replace it and see how much better it could be.
I was worried about the pentalobe screws but they unscrewed very, very easily. The back slid off easily. I removed the one battery screw and the tiny antenna piece. (How many notice that this little springy antenna piece presses against a metal strip on the back of the phone that is the antenna?) Using the spudger I carefully lifted up on the battery until it became separated from the double sticky tape. I put in the new battery, the antenna piece, slid on the back, put in the new screws (not pentalobe), and turned it on. It worked! The new battery is really nice and lasts a lot, lot, lot longer now.
I was concerned that the battery might not be the same quaity as the original. It looks like it is EXACTLY THE SAME as the original. I'm very happy about that!
I have already ordered a battery for my daughter's iPhone 3GS and am excited to install that. It is a bit more complicated but isn't hard if you prepare.
The iPhone 4 battery replacement was VERY simple. People have different abilities. If you don't often do this type of repair often, plan and prepare. My advice is to watch the videos multiple times, watch other videos on YouTube, read the instructions carefully, and prepare well for your repair.