No backlight after liquid accident?

Hi! There are four components which can cause the backlight to fail: The inverter cable, the screen, the logic board, and the inverter itself. The inverter cable or screen are often the cause, the logic board is less common, and the inverter is almost never the problem (despite popular opinion to the contrary, usually from people with book knowledge but no actual repair experience). I would connect your computer to an external display to rule out the logic board having a problem. Next, it's almost a tossup between the screen and inverter cable, so you may want to try the cable first due to the fact that it's a relatively cheap part.

While you are in the machine dealing with the inverter cable, you might want to remove the Airport and clean its contacts with rubbing alcohol, and see if it is recognized after that. The next step is probably to replace it. It's possible the liquid damage caused a logic board issue which is resulting in the Airport not being recognized, but hopefully not, and you won't know until you've ruled out the Airport itself as the problem.