It should be as easy as.... Open the case at the bottom (check the smaller access panels first to see if the battery can be accessed without removing the bottom of the case). Remove the battery; it looks like a watch battery, take note of the orientation of the battery. Take battery to local radio shack, Wal-Mart, store that has watch batteries....Get matching battery. Place new battery in, facing the same way as the old one was. Close Case/access panel. Make sure that you are grounded before you touch anything on your board!!!! Static electricity is a killer.