First off you're confusing "battery" with "mod". The battery is the round cylindrical thing that goes inside a mod, which, for you is the cuboid mini -- except the battery is non-removable in your case. Just to make sure I've got it right, your entire mod fell into the glass of water. Is this correct? If so, I would remove the battery out of the cuboid mini, open everything up and set out to air dry for several days -- just to be on the safe side. Since this is an electronic device I wouldn't want to try to fire it up until I was absolutely sure everything was dry first.
And... I should look up the device in question before I go offering advice. The cuboid mini has a built-in 2400 mAh battery so there's nothing to remove other than the tank. I would still recommend you let it sit out to dry for a day or three before trying to fire it up again.
In case this is your only mod, this would be where I make a strong recommendation that you get a back up. We always recommend having lots of back ups just for these types of situations. Things happen and you don't want to be without a device, a tank, an extra charger, some more coils, extra juice, etc. Get back ups. And back ups of your back ups. You can never have too many when things start to go wrong.