Hi Anne. Welcome to justanswer.
When you plug it into charger, does anything comes on the screen?
Press and hold the Sleep/Wake and Home buttons at the same time.
When your ipad device dropped into water, did you immediately turn it off?
And after how long you turned it on?
After completely drying it?
Don't accept it. The site sends an automatic offer for remote assistance
Smack it gently on the back and then try to turn it on
Since it is under warranty, they will probably replace it but don't tell them that you dropped it in water as generally this case is not covered under warranty
Most probably there have been a short circuit inside the ipad due to water. You dried it but maybe due to moisture inside the device, the components got short circuited when you turned it on.
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Yes tell them that it is not turning on after an update. Don't say that you dropped it. They will replace it.