If you have lockpick level 5 or a high telekinesis skill, you can open the doors that require levers. If not? Just go up and open all hatches as the first one, using one rope after the other. In the East area you are informed about bugs infesting the cellar.I'd SAVE! They're tough. Descend and fight them. After you've survived this, just go back to Swen and talk to him. Your upgrade has already occured after you killed the last bug, but you can reload for better stats if you keep your inventory closed until you're safely up again. Save and THEN open the inventory. Stats are fix as soon as you move your mouse over it.

If you want to leave this sector, simply click on the pyramid IN your inventory - or merely click on "use" in your pyramid task bar, if your pyramid is in your inventory. You don't have to leave it behind - if you wish to return - then drop it and click on it or use "drop&use".