It sounds to me that the LCD connector is either damaged or not inserted properly, please open mac back up and check all connectors.
Did the water affect the logic board? Is there any corrosion on the logic board anywhere?
If so you will need to clean the logic board up,
To do this remove the logic board and with a new soft toothbrush clean the mother board with isopropyl alcohol.
Then re assemble and check to see if the display is working.