In your 2nd pic, that is an air door that should open up. BUT BE CAREFUL. The hinges could be rusty/seized and you risk breaking the plastic. The hole in metal panel(door) Should have a knob on it. See pic
I guess someone already broke where it connects, see pic 1 can I drill and put a screw in the middle hole on the hinge and connect it that way? What opens and closes the door using the handle?