Very valuable information. Thank you! What I learned was that the batteries are NOT! marked + and -. This makes it tough to decide how to put in the new batteries. The batteries are glued down worked in my favor in de-soldering them. A Very tiny screwdriver put under the lead from the battery side and while applying heat with the soldering iron on the pc side. I gently pried each lead out of the hole. The battery being glued down made this possible. Copper braid or soldering could not take away all the solder. A pointy knife opened the holes to get the new leads in. I had to clip the new leads width down to fit in the holes. Small wire cutters were needed. A razor blade was able to slit enough of the glue to pull the batteries away. Then I realized I had not marked where the plus and minus had been. Take Pictures and mark the batteries along the way! I found the + button of one cell had been up while the - flat end was up next to it. As soon as the solder hit the last lead the LED sprang to life. Good luck!