You can have a problem with the buttons, these are lands that close lands, the best thing you can do is get these buttons and put a tester to prompt If continuity, that is, if the whistle sounds to you that they do not make a sufficient contact, the first thing you should do is check that these elements work correctly before looking for it, the precision manually, it is a good idea, but if they do not close the closing, we do not close the right Check your correct functioning.