Inspect. The door lifts for a few seconds. Sweep your flashlight over the dark unit and hover items to see what they are. Shiny things are usually worth a lot. Sealed boxes stay a mystery until you scan them.
Bid. The door drops and rivals start bidding. Bid while the price stays under what you think the unit is worth. You can pass any time.
Reveal and resell. Win and the door opens. Profit is resale value minus what you paid. Earn money, level up and unlock bigger lots.