@Max with the spirits help you quickly arrive to the main entrance, it is locked and all the windows are bolted down. In the third floor there is an open window. Perhaps this is why serge is climbing. You can either unlock the doors somehow, perhaps if you have a crowbar open one of the windows - or climb to the third floor.
@Serge you make your way to the window, it is a classroom filled with tables, chairs and a big old school whiteboard. (The kind that you actually write on by hand). There are all sort of spare parts and few hardware kits on the floor. You can also spot a small puddle of blood in one of the corners. You can hear some terrifying roar from the hall, but the door to the hall is locked.
Roll perception + intuition