If something voids the warranty does it need to be in the warranty agreement?

On my phone there are two water sensors and when I went to the shop where I bought it to get it fixed today I was told that one of them has been activated and my warranty when I got home I read the whole thing through (it's only one and a half pages) and it didn't mention the word water fluid liquid or moisture
should I persue this or is it a lost cause?
Thanks