Bad subwoofer?

Hey mate,  New subwoofers do need time to break in due to the stiff adhesive used.  You may wanna take it easy with low to moderate level for the next week then check again.  If the issue still persists, then seek a replacement since its still new.  Alternatively, you can take it down as soon as you can to get a replacement.  When you do get a new one, do take it easy for the first few weeks with it.  I think this is the most common mistakes people do with new subwoofers , and then they post a review on the net  to state - had it for a week used it and it died on me.    Subwoofers need time to break in, and that is all subwoofers, from entry levels to competition level so its wise to educate yourself on your gear so it can provide you years of enjoyment.   Respect you audio gear and it will serve you well. 

Hope this information is helpful to you mate!