20 - 30 minuten
iPhone 3gs, not used actively, battery swelled up to 5 times original thickness and popped the screen right off. The control board was severely bent.
The video makes the process seem overly easy. No additional tools were required. I didn't need to use the suction cup, because the screen was already off! Took about 30 mins. I had never seen such tiny connectors before. Need lots of light, and a steady hand for the tiny screws.
I read up on other guides on fixing the 3gs and watched more video instructions. There were important points that were not mentioned in the iFixIt video, like screw #7, and advise on how to put things back, like connector #3. I was lucky to notice that the camera connector had worked loose while taking off the control board. Look at everything carefully. Taking pictures would have helped me remember how things were aligned. After taking things apart, I was highly skeptical that I could put it back together or that it would work ever again. But it DID, and perfectly, and on the first attempt !!!