The usual reason for a washing machine door not opening is because the machine still contains too high a level of water. This level is sensed by a pressure switch inside the machine. As a suggestion I would unplug the washer then drain all the water out through the pump filter (removable) usualy located under the front plinth of the machine. Its possible the pump is blocked or not working for some reason. Yet another possibility is the drain pipe at the rear is kinked or blocked.
Peter
Peter, August 2007