20 - 30 minutos
The battery of my iPhone 3GS was out
The repair was fine, thanks to your guide informations on the web. It just was a little bit longer (nearly one our) than you announce, probably because it was the first time I had to work on such a material.
Nevertheless, it works perfectly and I hope my iPhone will run for another two or three years.
Be patient, work under a good light and don't forget to wear your glasses, for those who need some. For the rest, just follow carefully ifixit indications.