Stuck on "Add a Garment"

During a normal wash cycle yesterday, I needed to add a garment, so went through the usual routine by pressing the Pause/Cancel button. The washer clicked to allow me to open the door. I added the garment, closed the door (it latches fine), and then selected the START button. Nothing happens. It will not restart, neither will it allow me to cancel the cycle. The Add a Garment light remains lit. The display is flashing 49 (minutes remaining), but no series of button-pressing will either continue or cancel the cycle. I've performed this add-a-garment task dozens of times over the years, and it resumed like clockwork. Now nothing. How do I "unfreeze" the washer? Thanks for your help!