I have an E5500 purchased through the outlet. The only feature missing that I wanted was the backlit keyboard. I purchased one and although the keyboard works, I can't get the backlight to work.
Although i can find several instances of people having difficulties with these items, no seems to definitivly know what is needed to upgrade to one after purchase.
Do I need an additional cable? Do I need to replace the palmrest at the same time? Should it just work?
Download the dell quickset utility. hit the fn key and right arrow at the same time to turn on or off or fn key and up or down arrow to change brightness.
I have Dell ControlPoint System Manager, which think superceeds quickset and the button combination you describe does nothing.