Disassembly and assembly
Disassembling the charging case:
First open the lid and then try to press the case from the front edge with a plectrum or a thin card. There are two clips on each side. Soon the case will snap open.
Carefully unscrew and remove the PCB from the case.
Assembling the charging case:
Screw the PCB back into the place.
There is plenty of space, glue the coil to the bottom of the case.
Close the charging case.
External resources
A video regarding the assembly and disassembly of the PineBuds Pro can be watched from Linux Lounge here.