Light on color sensor is blue
The color of the LED on the LEGO EV3 Color Sensor depends on which mode it is in.

From the EV3 help file:


  COLOR MODE
  
  
  
  When the Color Sensor is in Color mode, red, green, and blue LED lights on the front of the sensor will turn on.
  
  REFLECTED LIGHT INTENSITY MODE
  
  
  
  When the Color Sensor is in Reflected Light Intensity mode, a red LED light on the front of the sensor will turn on.
  
  AMBIENT LIGHT INTENSITY MODE
  
  
  
  In Ambient Light Intensity mode, a blue LED light on the front of the sensor will turn on dimly.


If you want the LED to be red, make sure you are using the Reflected Light Intensity Mode in your program.

If you are doing this and the LED still does not turn red, you should contact LEGO MINDSTORMS customer support.