Well when I first played the dlc i had to start over because it was glitched at the fountain so i decided to start a new game and when i listen to the brodcast and get the quest i go to the abandend bos bunker and it says you need a key to go in and i dont know why.(also my game is glitch so bad i cant finish a couple of quest because of glitches)

Have you deleted your gamedata at any point between then and now? If so you may have to reinstall the DLC as well.

No i have not deleted anything

I'm assuming you have reinstalled the 2 patches. Try clearing your Xbox cache, reinstalling the game, and then reloading the patches and DM.

HTH.