After you see the credits the first time don't think its over because its not. Once the credits are over you're going to see a clip and after your finished with that clip run to the house and run away from the monsters. Then once you are in the place were you first sight the professor find the dead guy and get the bat, medallion, and the flare gun. Then put both of the medallions onto the door and connect the lines to each other. This is going to take a while but you will get it.