http://assets.coolermaster.com/gaming/download/keyboards/quickfire-stealth/quickfirestealth-user-guide-en.pdf
So, that's the user manual offered by Cooler Master for the model you listed. I don't know what you're doing to dim the LEDs, since according to this, that is not one of the functions offered. I don't think this one is even backlit; did you maybe get your keyboard model wrong?