First, remove the power (unplug and pull the battery if possible)
Likely there is still water in it, if the button is wet. You will need to dry it out. Getting some desiccant, and putting the laptop with it, and while making there is room for some airflow and letting it dry out; it may take a few days.
Using some rice would work, as it is good to absorb moisture (put the laptop in something like a cotton pillow case, to keep the rice separate)
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Sadly, the longer the time between when it gets wet and when it is dried, it can allow oxidization and corrosion of the components and is a chance that it will not work.
First, remove the power (unplug and pull the battery if possible)
Likely there is still water in it, if the button is wet. You will need to dry it out. Getting some desiccant, and putting the laptop with it, and while making there is room for some airflow and letting it dry out; it may take a few days.
Using some rice would work, as it is good to absorb moisture (put the laptop in something like a cotton pillow case, to keep the rice separate)