Started to replay Far Cry 2 a few days ago, and yesterday, I got the 27% glitch. I decided to do all the cell tower, gun dealer, and buddy missions before finishing the main story in Act 1, and now, when I go to the APR headquarters, I am let inside, but the door upstairs is closed and I can't continue on in the story and am stuck at 27% completion.

Does anyone know if there's a workaround? Playing on Xbox 360.