If it is under warranty talk to Apple and send it off to them. You can ship it to them, so it is no problem wherever you live. If there are no service centers in your country they might pay for shipping to the USA. Just call them and see what they say :)
99.9% change the motherboard is completely fried. Not to mention every single component is most likely useless being under water for that long. If i were you I would sell it "as-is" on eBay and get a new phone.