Diagnosis
The green laser diode for dust illumination has likely been deactivated. This is a user setting, not a fault. The laser can be turned off via the button on the main body.
How to Fix It
With the vacuum powered on, press and hold the 'Mode' button on the top of the main body for approximately 3 seconds. You will hear a tone, and the laser should reactivate. The button toggles between: laser only, light only, both, and off.
If That Didn't Work
Check the cleaner head connection. Detach and firmly reattach the cleaner head to the wand. A poor connection can interrupt power to the laser.
Heads Up
The laser is only visible and functional in lower-light conditions. It will not appear bright in a well-lit room. Test it in a dim area.