Bug report: if you die after getting the second-to-last checkpoint (after going down the elevator), but with the elevator in the "up" position, the next time you enter the elevator you'll be stuck in the door.
Also, would you consider adding an alternative control scheme? Something like left/right for movement, button 1 for jump/jetpack (depending on whether you're standing or in the air), button 2 for drill? (I'm passing the suggestion along from someone else, it's not my idea, but I do think it would be an improvement.)