Battery on my iPhone 3G doesn't hold charge.
It is so easy to follow step-by-step guide from ifixit. Make sure you read through the steps and see the pictures to help you figure out what part need to be taken apart GENTLY!
Be gentle when you pull any connector inside the iPhone and make sure you are paying attention on what you do.
Thank you ifixit for making an easy to follow guide and competitive price on DIY project on iPhone.