20 - 30 Minuten
My wifes Iphone 3gs kept on crashing during game use, especially during Tap Zoo and was not holding a fully charged battery for very long. Through some research and forums it was suggested that it was the battery causing the phone to crash.
The repair went very smooth. A lot better then I had thought. Slow and steady was the course to take.
Watch a video of the repair process and then use the guided illustrations during the repair. Take your time, don't rush. Make sure to have the proper tools for your repair.