I was under this impression. Because there is a light sensor, when it is darker the phone isn't as bright and the backlit keys activate. When the Phone is in a light enviornment the lcd becomes brighter and the backlit keys deactivate. If the phone is in a dark place and the lcd is darker you can push the power button once and it will light up to 100% as it would if it was in a place that is really light. I dont think pushing the power button makes it go above 100% it just brings it up to one hundred percent if it isn't already there. I actually think that is how it goes...it isn't an issue of making the screen extra bight...its just making it as bright as it would in a light enviornment.