20 - 30 Minuten
An old iPhone 3GS was dying way too early and was almost useless.
The repair went well even though it was somewhat nerve-racking, just with the concern the device would not work after. The instructions were GREAT!!
Get good lighting.
The screws are ridiculously small so make sure you can easily find them on the floor if dropped.
Figuring out how to disconnect connector 3 was a little difficult and the wording on the instructions was not completely clear. Once the black connector flips up it does make more sense though.
You have to pry fairly hard to get the adhesive to under the battery to separate from the back. I thought I might be breaking it but it finally popped up.