Keyless Refrigerator Lock System for a Single Door

Unable to return. Purchased to place on a refrigerator to lock up medications in an unlocked unit in a hospital. Our nurses immediately realized how easy it was to stop working - unplug it. No back up battery to prevent this from no longer working during power outage or when one is attempting to work around lock would be a major improvement for any future design changes. Also, it is not water proof. I wasn't expecting to be able to dip it in a pool or pour water on it, but a minor spill rendered it completely useless after I learned to lock up the chord and plug.