The second that liquid hits electronic circuits in your device, a process called electrolysis takes place immediately, which leads to corrosion. Corrosion is that green and yellow stuff you see in the pics below, and it is what eventually kills a liquid damaged device. It eats away at electrical connections and solder joints and can often cause short circuits on the logic board of your device.  "Drying out" a liquid damaged MacBook often times does not work because you cannot fully remove power from the device without opening the device and unplugging the battery, as even when the computer is off, power is still going through several circuits on the logic board. Cleaning the corrosion off alone usually won't do the trick either, as more times than not, when a component on the logic board becomes corroded, it gets damaged electrically. 

Typically, your MacBook's logic board takes the brute of the damage, often resulting in no power. Logic boards can be repaired by replacing the damaged or shorted components