20 - 30 minutos
A friend had a iPhone 3GS that would not hold charge.
THe "iFixit" tutorial is all you need! Great screen shots and hints with warnings. Read the instructions first and then followed step by step.
My advice.....DO NOT ATTEMPT any repairs unless you know what you are getting yourself into. UNLESS of course you go to "iFixit" website and see instructions then you don't have to worry about it. Also you can also ask them questions that is not covered. Thank you ifixit staff!!!!