I used a soldering iron to make a hole for a 204060 battery i bought off ebay in a pack of 5. it took a charge and gave a green light after no issues, the hole can slide them in and out for easy replacement. also there was a fin inside that needed to come out that made the old battery stay in place. be sure to watch for pinched wires, mine was from factory with a couple where the battery holders sit.
soldering iron temperature was 230deg c ts1000 with modded firmware.
black tape used was gorilla tape.
usually i can bring batterys back to life with 12 volts after disconnecting from the unit but not this time. worked for myvu crystal before.