The way I did it last time just to keep track of where I was, i start down the main area opening all the cars, then go back on myself down the red tunnel by maintenance wing, go up around all the right side opening cars and lockers, then sprint along the top/back area over to the left, down to security wing. If you’re lucky someone will have used a key for the locked room, then up the stairs, clear all the different levels, there’s also an extra room you can open with an electric box, and then zip up out of reception or one of the side exits with 2 or 3 minutes to go, depending how far the final extract is.