by Kale » Tue Nov 30, 2010 4:35 pm
I'm drawing a blank on this one. It sounds like you made it back to the front door that should lead into the institute and there should be no problem going back in again. The only thing I can suggest is to try both the door and the intercom(?) like device that is just to the side. It's possible that only one of them grants entrance. I don't have any real way to verify this, but hopefully it will work for you.
Edit: Wait a sec, have you jumped back down the cliff, or are you at the first area with all the barrels sitting around out in the open? If you're not at the actual door, you'll need to approach the north part of the cliff and use the action key while facing the gap to jump down to the path below. You need to be on roughly the center(?) tile along the top to initiate the jump.