You'll need a soldering iron anyway, so don't worry if you brake the switch wire (of which there is one only, sic.).

To get a detailed view of the connections, please refer to the previous guide. I have put the link in the introduction.

Observing the innards, I have made some important points. First: the PCB is double-sided, with a bunch of SMD components and wires, connected from one side only. What it means to us, is that one should be rather careful handling it. SMD is hard to resolder, and you don't want to peel a mounting point with the wire.

Second: the charging controller is contained on the main PCB (contrary to my assumptions in the previous article). This should be a plus since there is more choice for the replacement.

Third: the battery has leaked. Cut the wires, put the battery in a safe place (should be disposed of properly and not trashed), and wash your hands thoroughly.