Follow the steps below if the light on your sensor is red and you receive the following message on your screen:
Error: The Kinect Sensor is not level (C0051209)
Place the sensor on a level surface and try again.
Here’s what to do to fix this problem:
Turn off your Xbox 360 console.
Make sure the Kinect sensor is positioned on a flat, level surface.
Turn your console on to see if the problem still occurs.
This error can also occur if your sensor is very hot or cold. In this case, wait for the sensor to reach room temperature (approximately 70 °F or 21 °C), and then try using the sensor again.