On my MacBook it only works right if the screen is closed. So have you checked to see if the latch is acting closed? Also it has to be plugged in to work on the monitor part.

Put it in a bowl of rice for about a week. DO NOT use high heat directly on it you don't want to melt any internal parts. People think that using a hair dryer or putting it in the oven will make the water evaporate which is right but it will also harm the device. If you want to use anything use a vacuum sweeper to pull air around and through the device. This will cause the water to evaporate faster and not cause any harm to the device. Rice or Silica gel packets will do the same but you need a week or so to get the moisture out.