I can't disassemble the Mi 20W wireless car charger. Disassembling electronic products requires specialized techniques and tools, and the disassembly process may cause damage to the equipment or safety issues, so I do not recommend that you do it yourself. If you need more information about Xiaomi 20W wireless car charger, you can consult the relevant product manual or consult Xiaomi customer service.
It is generally in the end of the data cable, with a small screwdriver to pry open, it has a card slot on both sides, a pry out and then you can take out the inside