void laptop warranty

hi. i purchased a laptop last September 2010, unfortunately for unidentified reasons last march 2011 my boyfriend who was then using my laptop found the unit soaked with water. He immediately informed and because i was away that time i told him to bring the unit to the nearest authorized service center. He brought the unit at the center right away. He told the technician that the unit was soaked and that re removed the battery.The technician put back the battery and turned the unit on when he smelled something burning from the unit he told my boyfriend to air dry the unit for two weeks and be back and apply for warranty. We were very skeptical because obviously from the burnt smell from the unit clearly it short circuit. Still, he followed their direction and that same center sent the unit to the manufacturer. Last May we were informed that the warranty does not cover water spillage due to negligence which was stated on the contract to be ground for to void the warranty. So we have to pay for another 15,000 for a new motherboard to replace the soaked one.Of course I was expecting something like that, like I said to the technician who was foolish enough to turn on the unit when he knew it was soaked of course it will short-circuit. I told them, I wasn't able to decide yet what to do so i'l let them keep my laptop. I'd like to ask for your opinion, does the technician or the center have any obligation to what happened?what should i do?please help.

you would have to prove that they are charging you for additional cost for damage they made.