From the service manual:
"SmartBeam(R) uses a red Light Emitting Diode (LED) unit to indicate certain faults it detects in the imager camera and circuitry. A slow (once-per-second) continual flashing of this LED indicates the SmartBeam(R) camera requires aiming. A constantly (solid) illuminated LED indicates the camera has failed aim. The LED is located to the right of the rearward facing ElectroChromic (EC) inside rear view mirror photo sensor, behind the top center of the mirror glass. This LED is only clearly visible when it is illuminated."
Is it slowly blinking or solid red?
If you have Alfa, you could connect to the BCM and try to see if there are any fault codes that might help.