20 - 30 minutos
I bought an used iPhone 3gs but it was dying after some seconds or minutes when I used anything conected on the internet, gps or the camera.
I didn't have any problem when the iPhone was charging so I guessed that the battery was not good.
I just followed the instructions of the battery replacement guide. First I watched the video without doing anything on my iPhone so I could see what I would deal with. Then I looked at all instructions. Althought english is not my native language (I'm from Brazil), all instructions were very clear.
I didn't have problem to open the iPhone or to remove all screws but the Step 11 (when you have to peel up the "Do Not Remove" sticker), I believe that should have an better explanation for doing that and what is the impact if you do it wrong - in my case, the sticker ripped.
After that, everything was easy, although it was hard to pry the battery up. I used a hair dryer as recommended.
I installed the new battery and I put everything back.
I could not believe when I turned my iPhone on again but then I notice something: the cellphone signal bar was always low (not more than 2 bars).
After read on the iFixit website about people with the same problem when they replace other iPhone components (I didn't see any after battery replacement), I undestood that my problem was related to the "Do Not Remove" sticker and it's screw. So I openned the iPhone again and I put a new paper sticker that I cut with the same size of the original one. Then I put everything back again and when I turned the Iphone I had the greatest surprise: cellphone signal with 5 bars and since then my iPhone didn't die anymore!
1) Follow the instructions strictly
2) Take care when you remove the "Do Not Remove" sticker
3) Buy the suction cup - it's easier to remove the iPhone display