There is no lock per se, rather there's a tab with a plastic block on it that sticks out at the top of the body of the DW. That engages a plastic plunger in the hole at the top of the door. That plunger activates 2 microswitches. If the block on the end of the tab isn't pushing it down right or the plunger is sticking those switches don't activate and nothing happens.
turns out that was exactly the problem! the switch wasn't be depressed all the way anymore. thanks!!!!