Started up the printer which is normally turned off. It indicted that the tray 1 needed paper (it didn't but I took the paper out and reinserted it. The printer now says side door open close side door. I've done that twice and it won't budge. It still wants the side door closed and will not print. Help me, I think it's an easy fix but I don't know what it is. I have shut it down and unplugged it but nothing has helped. Previous to this the printer worked great.