Backlight doesn't work anymore

The Backlight of the Macbook Air 2014 of my sister doesn't work anymore. She dropped a bit of water on the Keyboard and after 20 Seconds the Light was out...

But the Display works for sure cause it can be seen with a bit of light through the Apple.

The water was on the keyboard near to Power and Sound Key.

Is it Possible to repair it on my own? Apple Repair costs 500 Euro...

I'm Thankfull for any help :)