Hi @plznoo ,
As you know water and electronics and electricity are not a good mix.
The water causes corrosion and provides circuit paths for the electricity which were not in the console’s operating design and could damage the components.
First do not turn on your console and then you need to with the console turned off, remove the battery as soon as possible from the console to minimize further damage.''
Then you need to dis-assemble the rest of the console and clean all the affected parts using Isopropyl Alcohol 90%+ (available from most pharmacies), to remove all traces of corrosion and water. Do not use "rubbing alcohol" as in some cases this is <70% IPA, can contain scents and is not as effective. If you do use it, check the label to verify the amount of IPA
Here is a link that describes the process.
Electronics Water Damage
You may have to replace the battery as it is very hard to recover a battery from water damage.
As always with electronics, especially surface mounted PCBs be gentle when handling and especially when brushing away the corrosion. You do not want to remove any components from the boards.
Hopefully after you have done all this the console might possibly work correctly again.
Here is a link to the ifixit teardown guide for your console, which may be of some help.
Nintendo 2DS XL Teardown
If this process seems too daunting, take your console to a reputable, professional electronics repair service, experienced in water damage repair and ask for a quote for a repair. If you decide to do this, do it sooner than later.