Hit the wrong lift door button when in a hurry. Maybe closing the doors on someone hurrying to hop on.
It's not hard. The Australian Standard symbology is confusing as it depicts door states in conflict: one shows the desired state of the door being closed: the arrow heads pointing to the door leaves closed, suggested by a vertical line; but the other shows not the desired state, but the current state: another vertical arrow, but not the state we want for the doors open. At a glance they are impossible to distinguish promptly.
A better symbology is in the lifts at a Council Chambers I recently visited in Sydney.
And here's my sketch.
