GRB (Garage Door Release Blocker) this helps block the attempt of an intruder from inserting a coat hanger/ or wire/tube device with a hook type configuration from releasing the emergency mechanism of the garage door opener. To use the GRB first position the garage door in the down position,  manually release the emergency pull cord by pulling down, next there might be a snap ring or cotter pin on the pin on the arm of the garage door assembly. (see image).  Install the GRB, insert the pin removed and retaining safety snap ring or cotter pin, fold the rope/handle in the cavity of the GRB, either manually re-engage the arm to the trolley part of the garage door opener, or activate either the garage door remote or fixed button opener mounted on the wall.  (I design this for a Lift Master Garage Door Opener, see image for configuration )

I've updated the design to allow to let the rope hang thru a slot, to allow release in emergency. Handle should be removed and rope adjusted/cut according.