How does the ncov corona virus actually kill you? do your lungs close up like an asthma attack? do your lungs fill up with pus or fill up with mucus?

Novel coronavirus: nCoV kills primarily the same way influenza sometimes does, by its effects on the lungs. These include pneumonia due to the virus itself; acute respiratory distress syndrome, a complication of many serious illnesses; and bacterial pneumonia, which commonly complicates almost any respiratory infection. All these can be fatal for the reasons you state, plus others.