Hello I recently bought 3-axis gimbal I downloaded 2.40bi guy and made firmware upgrade to 2.40b6 so, when i connect the board to my PC i get "Sensor is not connected" mistake battery is always plugged the one free slot on the sensor is INT
That pin is not used on the IMU. Make sure you have the wire connected properly, meaning to check that ground is connected to ground, if not this will cause your error.
Though it is not good practise to connect any components when power is on, I do not think this would harm them, if the connection is right and no short-circuit has been caused when connecting.