The charging port is inside the power button. Kindly find the rubber cover on the back of the doorbell and carefully pull out the cover to charge the doorbell pro.
You can charge it through the USB port of the Base station or via a 5V 1A charger.
Note to put back the rubber cover and press the power button to turn on/off the doorbell to avoid damaging the component.
Power on: Press and hold the power button long enough, until you hear the audio signal "Hello, WUUK".
Power off: Short press the power button more than 5 times, until the devices make 3 short beeping sounds.