Laptop won't turn on after water spill.

First problem, was you continued to use it after water was spilt on it. Any water spill should be treated seriously as the motherboard sits directly beneath the keyboard on most laptops, with a few exceptions having drainage ports that help to mitigate liquid damage. You could attempt to further dry it out by placing it in a dehydrator for a few hours on a lower temperature, but a lot of times if a liquid joins two or more circuits, there can be irreparable damage to the system. It’s not the answer you probably want to hear, but it’s a truthful answer.

Your first step to potentially remedy it is to get it in a warm and dry area and let it sit to complete dry out. You can reattempt to start the device up after that point. The worst thing for a board is if it is a substance with salt or sugar, i.e. the coffee pills on laptops I’ve encountered too many times to count and the residue of sugar and dairy creamer left behind.

Honestly, best of luck because it’s not always easy to return from water damage especially when you felt you did everything right to prevent damage to it.

turning it on could have been a mistake…a very dry environment, an immersive bath in a pan of rice, etc, for an extended time (pick a number and double it) might solve the problem if nothing has shorted.