We have a GE Spacemaker. We have a GE Spacemaker 2.0 Over-The-Range Microwave Oven.It has power,

Question

We have a GE Spacemaker 2.0 Over-The-Range Microwave Oven.It has power, and the keypad display appears to be normal at first glance. None of the keys or buttons are operational, however. In all cases, the display indicates that "control is locked." This is true even with the help button.Those present when the situation arose insist they did nothing unusual. How does one "unlock" the oven?