Ealdwig give it a shot.
Does Ealdwig see a mechanism nearby or anywhere in the room that may hold it open or turn it off?
OOC:
For my clarity of the situation, occasionally I have had trouble visualizing what is happening. The trap is immediately on the threshold on the other side of the door? One step in and you're on the trap? So to get over it, you'll have to go 10' straight ahead, there is now way to skirt around it? How did it open? Did it slide, fall completely, is it on a hinge? If a hinge which side is the hinge on, the door side, the room side, left or right?