Forum:Need help with armory glitch

I was doing the armory glitch where you can get into the armory without a time limit. I did it on the mission from Marcus (Super-Marcus Sweep). The glitch worked great however now when I returned to do it again, the door is locked and I can't get back into the armory. So not only can I not get in to do the glitch again, I can't even finish the mission. Any one have any suggestions??