Sometimes the door does not open because there is still water in the machine.
As a first resort, take the drain pipe off the sink and let lie flat on the floor. If the drain pump did not pump out all the water, then laying the drain pipe flat on the floor will empty the machine completely. Once the machine is empty the door should unlock in a few minutes. If it doesn't it is more serious and you'll need to call a technician or unplug the machine, get in from the underside or back and manually unlock the door.
Sam, November 2006
