20 - 30 minutos
I use my iPhone 3GS as my navigator. The battery is dying and I would like to replace the battery by myself.
It is great to follow the iFixit guide to install the parts. Just have some trouble when putting everything back to one piece. But I think this is my own problem. The iFixit guide gives great advice.
Read the guide first before you are going to do anything "stupid" =P