Q: How do I revert the device to factory default settings?

A: 1. Power up the device, wait 50 seconds until it finishes motor calibration/rotation.
     2. There are a small holes at the bottom/back of the device. 
         The hole with "two arrows" sign is the reset button to "revert the device to its default factory  

         settings".
     3. Use a thin pin to stick it into the reset button hole, then press and hold for 3~5 seconds 

         until you hear a beep sound.
     4. Release the pin, the device will restart automatically.
     5. After motor calibration/rotation, check if the front blue LED is blinking. If yes, the process is  

         done. The device is in 'waiting for installation' mode.

     Reference: https://www.youtube.com/watch?v=VNvftkbS__c