回答先: Why is the "F dl" light come onHere's a variation on the themes mentioned above… After removing the top of the washing machine and then removing the control board plastic housing, we opened it up and inspected. I really didn't want to get into desoldering the relays, so I decided to just tap them firmly with the handle of a rubberized screwdriver. That must have dislodged whatever was blocking the contacts, because the doorlock engaged as soon as we plugged the machine back in. Now I have a quick and dirty solution. The only issue is whether I’ll spring for purchasing a refurbished circuit board with improved relays. Thanks to all for your contributions and I hope my little post makes someone's day!