I bought my macbook pro in mid 2012 for college. Over time the trackpad clicker started to lose its click. I took it to the apple store in Madison. They checked out the computer and said that one of the liquid sensors went off right under the track pad, which was weird because I never remembered spilling anything on my laptop. They told me it would be a minimum of $500 to replace the trackpad and any potentially water damaged components. My computer was working fine except for the stuck trackpad so I said no. When I came home to Seattle I decided to give it another go since I felt I wasn't treated fairly. When I brought it to the apple store they checked it and found that none of the liquid sensors went off. Also they said there was no record or notes from my talk with the people at the Madison store which they apparently should have taken. The apple store in Seattle replaced my trackpad for free under my apple care policy. My question is if a liquid sensor goes off once, can that be detected or is it possible that the liquid could have dried up and the sensor reset when I got to Seattle? If a sensor can't be undone then I feel like I definitely was scammed. Maybe the people in Madison thought they could screw over a dumb college kid.