Get a USB-C charging cable and adapter (not provided with Monimoto).
- Remove rubber plug and insert USB-C charging cable into the charging port.
- Wait till reset button LED displays solid RED indicating full battery.
- Remove USB-C cable and replace the rubber plug.
NOTE: If you lose the little rubber plug don't worry, it is not needed for your device to be waterproof and is only there for extra protection against dust/dirt/grime from regular use. The charging port itself is waterproof without the plug.