Okay, so making an even bigger mess isn't exactly the point of a Roomba. But that's fine. The Roomba needs to use this as a learning experience. If you can't learn from your mistakes, you'll never grow.
And so he bought another drink to get the drink and the sandwich out. Then that drink got stuck. Then he bought another drink... Eventually he purchased everything in the vending machine and everything got stuck. And such is the circle of life.