Hi Tress.
I'm moving this thread over to the
Help->Strategy Centre where I'll give you some tips...
...ah, here we are...
Right, when you say 'arena' I am assuming you are talking about the large chamber where two Stormies get shot down by the guns, etc. Okay, you need to go back up to the room with the big construct in the middle of the 'dangerous water' (heh...gotta love these technical terms

). Take a ride back up in that elevator. Now walk around the whole perimeter of the chamber on the narrow ledge until you're looking through the two windows. You should see a big (explodable) crate in the room beyond. Shoot it...and it'll short-circuit the controls next to it. This activates the bridge from the door to that room across to the central pillar. Now you simply go back around the ledge, and cross that bridge to enter the room. Hope that helps you out.
