iFixit

Working from the edge opposite the battery connectors, insert a spudger between the battery and the plastic frame and pry up. The battery is attached to the casing with an adhesive, but should slowly come free.

If you have never soldered before, we have a guide that makes it easy to learn. We suggest brushing up before proceeding.

We're now ready to begin the soldering process. You'll need a soldering iron, solder, and desoldering wick. You should be able to find these items at a Radio Shack if you don't already have them.

Clean the solding iron by melting a small amount of solder directly onto the soldering iron's tip and then wiping the tip of the soldering iron on a damp sponge.