The LCD / LCD flex cable has been damaged or the part of the motherboard that controls the LCD. You would need to take it apart and look for corrosion on the motherboard and flex cable. It's possible leaving it open and letting it dry out might help. Liquid damage is unpredictable. If you don't see any signs of corrosion then you could buy a new LCD and give it a shot.
Need some help, advice, something fixed? Hit me up on Hangouts @ es0tericcha0s and check out my site: http://mobilemojo5280.com
for more info!
HTC Droid Eris / Motorola Droid / Samsung Galaxy S Fascinate / Motorola Droid X / LG G2x / HTC Evo 3D (x2) / Samsung Epic 4G Touch (Sprint S2) / HTC Amaze / Samsung Galaxy S3 (International) / Samsung Galaxy Note 2 / Nexus 4 / HTC One / Samsung Galaxy S4 / Sony Xperia ZL / Nexus 5 / ? (One+1 maybe...)