20 - 30 minuten
I bought a new battery for my iPhone 3GS just because I didn't want to spend the money in a new one, I figured I'll try it and if it doesn't work I'll buy the new 4S. The thing is it did work and now I have a fully functional iPhone.
I had to watch the video closely, pause it and double check things. The video is not 100% accurate, there are some things not shown but they tell you this at the beginning so I was warned. It is always scary to open a device such as an iPhone, you have no idea what you're going to encounter. I had some trouble with the first connectors, the ones that go from the screen to the mainboard. At first I thought I had broken one of the terminals but it was just a lock that you have to move up with just a little force. Then the screws and finally the battery, it was hard to pull it out because of the adhesive glue that is attached to, finally did it and did all in reverse.
I got advice yes. The camera didn't work on my first try, or the second. What you have to do is put some pressure with your fingers against the mainboard where the camera connects, it will not connect by itself simply by putting back the mainboard. I took the camera out and attached it with some little pressure and then put back everything again and it worked :)