as far as I'm aware, it's impossible if the mechanics are as simple as presented. it's impossible to push the door blocking the + anywhere except onto the +, where it gets stuck, and it is impossible to hold down the button with anything other than the player.
I've experimented with level 1 to the point where I think I've figured out all the mechanics, how the doors interact with each other and the boxes, and the properties each door has.
unless there's some secret, I don't think the first part of level 2 is possible.
