The machine won't start

Its hard to tell whats wrong with just an image but from what you said (About slamming the door shut and making it work), I would assume that the switch on the door that tells the machine that "the door is closed" might be broken.

Take a look at the door mechanism (There might be a switch), and see if the switch is broken. If you have a multimeter, you can test the continuity on the switch (Only do this with the machine unplugged from the wall! Don't want you to get shocked). Good luck :)