Our bad. If you're interested in trying it again:
wasd or arrows: movement
q : use item in hand (either unlock door or ring bell)
e : open and close doors
tab: switch between keys and bell
shift: run
If you get caught by a monster, you can mash q to escape.
Also, while 'restore checkpoint' doesn't work, it should still save your game. So, if you re-open the game, selecting 'load' will take you to the second level if you made it that far.