Update After some more research, it turns out the board for the USB charger may not be too smart and if you let the charge of the battery pack drop too low it will no long charge it. Fortunately, you can bypass the board and plug the battery into a typical 6V power wheels charge. After that, you should be able to charge it via USB again. ...
After setting the Christmas tree this, a section of the builtin lights weren’t turning on and found two of the wires had been chewed through. I didn’t want to have to throw out the whole tree so I set about fixing it. I wasn’t looking forward to it though as I thought I would have to solder the wires together and cover them with heat shrink tubing… a process that was going to be very annoying under a Christmas tree. I debated just taping them together with some electrical tape but I didn’t want to deal with it maybe coming loose while taking it in and out of storage. ...
This effectively amounted to replacing a battery but I still learned some things along the way. It was thankfully easy to take the rubber case off which I expected to be glued or something but I just had to pull it off. This revealed the main board with the LEDs and the battery tucked underneath. It turned out to be a 18650 lithium battery. ...
Today I learned that the following white connector you commonly see in electronic devices, is called a “JST connector”.