Can't enter Magnys Lighthouse [Xbox 360]

Hi, I have a big problem about a mission of dlc Captain Scarlett, GOTY edition. With my Mechromancer, I have the mission Let the Light Be and i need to enter Magnys Lighthouse, but when loading the area the message “disc unreadable” appear. I tried everything, reinstall the goty, reinstall last update, installed the disc on HDD, changed original Borderlands 2 game disc, cleared the cache, but always that “disc unreadable”. How can i fix this huge problem? I know other people had this problem, only when try to enter that area