@joelgunaratnam you want to treat this exactly like any other water immersed device.
For now you want to stop continuing to try to charge, sync or otherwise use your device. This potentially can make a bad situation worse.This may further damage your controller.
The very first step I would take is to disassemble your Gamepad. Use these guides Wii U GamePad to help you disassemble your device. Take a careful and close look at all components and connectors. Truly assess the damage. Look for major corrosion, evaluate the pins in the connectors etc,. Take a look at all connectors as well as cable ends. Once you got the gross contamination (leftover water etc.) cleaned, use +90% isopropyl alcohol and clean your parts some more. For a proper cleaning, use this guide. It was written for an Apple iPhone 3G but it is still pertinent to your gamepad as well. I can not stress the importance of a good cleaning enough, so do it over and over while replacing the alcohol after each cleaning. Do not use compressed air for the cleanin. That can drive liquid, as well as corrosion particles into areas that will cause trouble later on. Also, you do not need to leave it to dry for a day. Isopropyl alcohol in the higher concentration will evaporate quickly and dissipate the water. The importance here is the cleaning. It would of course be best to get it professionally cleaned via an ultrasonic cleaner, but this will at least help. After that, reassemble your gamepad and re-evaluate. Do not forget to replace the battery. This is a must and not an option. It will fail if you do not take care of it now.
For as long as you have not cleaned your boards etc. everything is just a guess. Keep in mind that water damage is the hardest to troubleshoot and to repair. It does not matter if is was exposed for 2 seconds or 2 hours, what matters is where the water (particulates) did the damage.
The water inside your LCD will evaporate, but it will most likely leave streaks etc. So there will be always be residual damage.