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I'm sorry that your iPhone got damaged. Water damaged iPhone can be repaired easily unless the logic board/memory is fried. DO NOT ATTEMPT to charge it or turn it on. This may fry the circuits in the board and render it useless. First, we can try to dry it and see if you are able to make it work. To dry it out, you can try this. Completely cover the iPhone in a bag of rice. Rice being a natural desiccant will help absorb the excess moisture in it. Let it dry for at least 2 or 3 days. Then turn it back on. If that didn't work, then you have to send it in for repair. Don't try to turn it on until you dry it completely.
I'd recommend to send it to professional repair centres or Apple stores. They take the phone apart and clean the components manually. This will ensure that no water left in the phone. But I can't guarantee it will work, but there is hope. If you turned it off immediately after you took it out, then I'd recommend to send it in for repairs as there is a chance to fix it.
The device will not be covered under warranty because Apple doesn't cover liquid damages under warranty. All warranty on the device is now void unfortunately. They knows that the device got water damaged because there is an indicator inside the phone that changes color when contact with water. Since this is an new iPhone, you may be able to replace it for a fixed price if you take it to the Apple Store.
I'm sorry that I don't have a better answer for your question. This is the only things you could do to a water damaged phones. If you have any questions or would like any additional information, please don't hesitate to ask. Please don't rate me bad or poor if you are not satisfied with the answer.