Using the Philips head screwdriver, carefully remove the four attachment screws that secure the PCB into the bottom of the case. This will allow you to lift the PCB free of the case and get access to the USB connector

As you lift the PCB out, you will see where it attaches to the battery. No need to disconnect this (unless you are replacing the battery) as there is enough length in the battery wires to get access to the USB connector