Snow can easily see four spots in the thin painted metal, 2 each on opposing sides, where rivets were attached and painted over. Stands to reason they are attachment points for hinges or latches on the cover.
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The suppressive fire works to lets O'Connor reach the door without response, the damaged hinges keeping it from swinging closed. As he reaches it, he sees Clementine on the roof above and his ears tell him Sammy and Torley are behind him to his left between the cars. Though it is still dark inside, he can see the remains a makeup table against the far wall of a small room.
(OOC: You have all reached the end of your movement for the round, though Clementine can be on the ground with the aforementioned roll, If Snow is doing anything with the hatch we can handle that, but otherwise we will be starting a new round.)