How to replace the battery?

To take this apart, use a pry too on the bottom cap. You can see the rubber under the cap. Pry this off and gently remove the rubber sleeve. Remove the torx screws open the case. The batter is the round thing. I cut the plastic and foam off of it and peeled the metal nickel strips off the old battery and welded a new one in. You can also use Solder if you broke the nickel strips as I did. Wrap it back up in some foam tape so it doesn't rattle. Reassemble.