What is the procedure for replacing the battery on an iPhone?

What is the procedure for replacing the battery on an iPhone?

Solution 1:

iFixit has excellent text and video guides for replacing the battery on all models of the iPhone. Here's their iPhone 4 battery replacement guide.

Solution 2:

If you want to keep your warranty alive at all, take it to your local Apple store or authorised repair centre and ask for the service. Any other action may void your warranty.

Solution 3:

It depends on which one you have. I have replaced LCDs and glass screens on the 3G before. Following tutorials at Repairs Universe is really helpful. They have videos and detailed instructions. Here's a tutorial. I haven't looked at it, but it popped up by Googling "replace iPhone battery."

Hope this helps!
Thomas