I`d look at two places
First at the grill with the piece of plastic behind it, its held in with a piece of rubber on the inside , looks like its been siliconed in , at the bottom it going to want to collect water ,if its not sealed well its going to come in. I`d pull it apart and get rid of the grill and just use the plasic , and use proflex to seal it in with the rubber behind it
Second place to look is at the bottom just at the bottom behind the rubber gasket there are probably a couple of screws going thru the compartment dr and in to the frame to hold the dr in ,if they don't have some sealant over them the holes let water into the box , that happened to mine
