The calculator will need to be opened and inspected as to what damage has occurred.
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 calculator’s operating design and could damage the components. The corrosion starts immediately and is ongoing until it has been properly cleaned away
First do not try to charge or to turn on your calculator and then remove the battery as soon as possible from the calculator to minimize any further damage.
Then you need to dis-assemble the rest of the calculator and clean all the affected parts using Isopropyl Alcohol 99%+ (available at electronics parts stores) to remove all traces of corrosion and water. Do not use "rubbing alcohol" as in some cases this is only 70% IPA or less, can contain additives and is not as effective. If you do use it, check the label to verify the amount of IPA. The higher the concentration (%) of IPA the better
Here is a link that describes the process. Electronics 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 board. Also remove any shields that may be covering some components as there may be corrosion under them as well.
The LCD screen connections to the motherboard may need to be checked to ensure that there is no corrosion between the leads as well.
Hopefully after you have done all this the calculator might possibly work correctly again.
Here is a teardown video of the calculator, which may help.
If this process seems too daunting, take your calculator to a reputable, professional electronics repair service, experienced in liquid damage repair and ask for a quote for a repair. If you decide to do this, do it sooner than later. It isn’t going to fix itself.