dell service

You should check your current configuration to make sure you ordered it since it is optional. Not all 1735's come with the backlit KB. You have to order it and pay a little extra. Look at your invoice or check your configuration and manuals online. You should not have to do anything to activate it. Definitely do not take the computer apart or do anything drastic. Contact Dell Support again if you are sure you ordered it and use Chat if available instead of email. Here are the directions to turn it on:
"The backlit keyboard provides visibility in dark environments by illuminating all symbols on the keys.
Keyboard/ Touch Pad brightness settings Press <Fn> and the right-arrow key to toggle between the three lighting states (in the given order)." The 3rd state is OFF.