You explore the three floors that you've been through so far, and discover that the doors on all the stairwells, storage rooms, janitor's closets, and, conveniently, the backup generator room, are ordinary doors with ordinary handles that can be opened easily. The doors to more important places like the labs are mechanical doors driven by electric motors. The time/space lab, of course, has already been opened from the inside.
In the storage room, you find a box full of rubber drive belts! Unfortunately they've been exposed to the atmosphere for far too long, and crumble when you pick them up. There are quite a few other cardboard boxes in the storage room, containing things like nails, first-aid kits, batteries (mostly expired), light bulbs, paper, and other random stuff. It would take a long time to search through all of this.