It means there is a problem with your motor. This happened to me when there was a leak and the motor flooded, but obviously your motor could be not working for another reason. Ours would actually do half the cycle, then when the leak increased when the dishwasher drained, the motor would cutt out, trip the breaker, and display the error code 50. Ours was actually fine once the leak was fixed and it dried out, but if yours is not running at all, it is probably more serious.
You will need to have someone in to repair it and it will probably cost £150-200.
LydiaE, July 2008