5 - 30 minutos
I've used my Iphone 4 for work and personal use for about 18 months. The battery was no longer holding a charge. A local repair shop offered to replace the battery for $90. I figured there had to be a better alternative.
The repair took me about 20 minutes from start to finish. The online video was easy to follow and well made. I ordered the #00 screwdriver and it helped significantly. I also ordered the plastic opening tools, but did not need them. The hardest part for me was getting the tiny screw that holds the battery in place. My hands are big and the crew is the smallest one I've ever worked with. That took several minutes. Other than that, it was easy to swap one battery for the other.
I didn't realize at first that the iPhone back only slides forward about a 1/4" and then must be lifted off the front. I initially kept trying to slide it forward. That was a minor issue. Overall, this is a fairly easy fix to extend the life of an iPhone. My guess is that most anyone could do it.