Forum:Knoxx armory glitch busted

While doing the first Marcus Mission where you get a second run-through the armor, I did the glitch, only I accidentally went into the circular room, so now the "loot items" objective is checked. I exited the game, and went all the way back, and in the hall way just after the color coded door, there is a door that will not open. Is there any way to fix this?