How do you change the battery in a 2004 infiniti g35 remote?

Near the keyring hole at the bottom of the controller there will be a small opening, it should be wide enough to fit a coin in. Fit the coin in and pry the controller open till it pops. In the controller you should find what you're looking for. Simply pick it out with your fingers without messing with any of the wires, and put in the new one.