20 - 30 minutos
My Iphone3gs battery went nuts(crazy) And I ordered for a new one to install
By following the fix it manual I was able to install the battery.Everything went smooth with all the needed tools available.The adhesive used to attach the battery however,was %#*@ hard to remove though and it took a lot of my calories but at last removed it.Attaching the new battery was just a piece of cake and reassembling the logic and the camera didn't seem to be so hard.I finally reassembled everything just within 45minutes and boom! the my former nice iPhone 3gs.I had to change to 4s coz the parts took so long to arrive but well Japan and US is a little a distance away and I chose the cheapest sending method so I just have myself to blames.
just chill out and do what you can do!!