The Battery or The Charging Port May Have Gone Bad. Its a Possibility Try Shining A Flashlight At The Screen To See If You See A Dim Image. That Would Indicate A Different Problem If You See Somthing.
You could try installing a new OS it might fixit but thats usually a sign of a Hard Drive Failure but because of the water damage a hard drive replacement still might not work I would sagest a water cleaning as soon as possible to prevent corrosion on other parts of the computer and it might even save your computer.