Duraforce Pro 2 - Opening it up to investigate speaker issue

My wife and daughter have the same phone. I love the durability. My daughter says her speakers are sounding wrong after the phone was exposed to moisture (she keeps it nearby when showering). I was wondering what the safe steps were to open the cover and look around inside. I was thinking of blowing it out gently with come canned air. I can’t find any instructions anywhere about opening this phone model.