What do you do after you get the scooter on night watch island?

Once you have charged the scooter (with the quick charger from MacGuffin's), drive down into the atrium, and left into the west wing, then back. When you see the cart drive past down the left escalator, go to the top of the escalator and wait there for it to come around again. (For some reason, it does not always come back right away.)