Joey can't pick the thing up, but let's see if we can find a way to get it Rosa, who can only reach the first and second floors of the building. What happens if you blow on it?
The plastic thing bounces against the elevator doors. If you have Joey try to go into the elevator, he says the elevator is stuck between the first and second floors. Maybe Rosa can find a way to get the elevator working again.
Down in the lobby, have Rosa look at the box on the wall to the left of the outside door to find it's a fuse box. What happens when you flip the power switch?
Sure enough, the elevator starts working, but it breaks down again very quickly and all the fuses blow. Clearly, we now need a fuse.
If you look in the box in the room with the stairs, you can find a working fuse. But which fuse to replace?
I'll give you some info here that the game doesn't: the fuses operate not the elevator itself but just the elevator doors. So if you replace a fuse, the elevator door on that floor will open.
Pull out the "Floor 3" fuse and put in the fuse from the box in that slot to open the elevator door in the room where the ghost is. Joey can now blow the plastic thing into the elevator shaft, and it lands on top of the stalled elevator.
Rosa can now take the good fuse from "Floor 3" and place it in "Floor 2" to open the elevator door on the second floor.
To reach that room from the lobby, send Rosa through the door on the right to reach the room with the stairs. Here, go through the door on the left to reach the second floor room with a toilet and the second floor elevator. Tada!