Disclaimer:
Under no circumstances should anyone not familiar with electronics and with the safety practices surrounding them take apart a lithium battery housing of any kind. I do not suggest working on batteries and if you do so it is entirely at your own risk. A catastrophic failure when working with lithium batteries can happen after you think it works, this may result in disfigurement or death. If you have no experience with volatile power cells or small electronics just throw it away!
Alright with that out of the way, I have taken apart several devices. I turn off the battery, five quick clicks, I take an old tank bottom without a tank on it and screw it onto the battery to protect the threads. Vise the the head of the battery on the thread protector and work it back and forth just until it starts to come up, following that, I pull out the head
very carefully, wires will be attached, I don't want to break them off. Then I slide out the carrier and board from the head. I normally have to push the button to get the board out, it is
critical that the device is off if it is not and the board is malfunctioning then the short causing the device to fail could transfer to the battery causing it to detonate, literally. This will get into the case. I have to be careful not to pull any wires off the board while doing this because they are tiny and connected to points throughout the device on small solder points that are easy to break.
After I find the problem, usually a mashed wire or a wire that has broken loose from the board or battery (other issues require advanced time with a multimeter to diagnose) I decide on what to do.
If it is a battery lead that has come off of the power cell itself I discard it Everything else is just a matter of finding the issue and fixing it. I never use electrical tape or any insulation medium that can slip or is designed to be impermanent, I always solder never splice. I always use shrink conduit, hot glue or dipped plastic/rubber depending.
On devices with a bottom function, that is a charger board or adjustable voltage on the bottom of the device I use special care not to sever wires and to look for connections I am unaware of. I have had one battery with a flaw that shorted it out and it got very hot really fast, I was ready and dropped it into an empty ammunition storage box designed to take extreme heat and gas production on a concrete floor and moved away from it. It did not explode, that part is pure luck.
If electronics are a hobby for you and you have some skills and some space you may be able to fix your device but I make no promises and feel it is a far better idea for the vast majority of people to simply dispose of these devices when the device quits working, as they use an inherently unsafe power cell and are remarkably prone to critically failing at even the most minor persistent direct short.
That's not me, It was a cell phone in his pocket apparently, but it could be anyone that does not respect the safety needs of a high drain power cell. Please know your limits. Stay safe.
