1. the serial port not connected. To use USB connect the Robot, select corresponding COM port under “Connect -> Serial Port “;
  1. Serial port has been used by other device. The Robot is connected by 2.4G or Bluetooth, check it is disconnected and remove it from the Robot.
  1. run mBlock under Administrator authorization. In some situation, the software need run some Arduino function which need Administrator permission. Run the software with Administrator permission would solove this situation.