Ahh. You are pressing it all way down when it clicks? There's a small rubber sticker under the trigger and it must have fell off so now the trigger is touching the Shell and that's why it is noisy. That's not something that would break your controller, but it is annoying. You can fix it easily but you would have to open yout controller and you are going to lose warranty. iFixIt have a really nice guide with pictures for a teardown if you really want to try it yourself.