Mike, during my on-going saga with my power bay door locks, I have experienced the same symptoms. While I had the relay (K21) unplugged, of course there were none. When I plugged it back in, the keypad continuously clicked for quite some time, and would not unlock or lock the entry door. At the same time, the one bay door that still worked would continuously cycle, a continuing series of the actuator opening and closing. After awhile, as I systematically replaced the door latches, and unhooked the actuators, the problem stopped. At this moment, I have all but two of the bay doors changed, and no actuators powered. I can lock and unlock the entry door with the key fob, and the one working door I have had all along, that has not been changed. When I get them all done, and new actuators installed, I'm going to call Essex.
As a side note. I discovered that two of my bay doors never had lock cylinders, so they were never able to lock. The battery bay door is one of them. There was a key slot, but no lock cylinder. In the bay between the batteries and the bay that has the holding tanks, that door didn't even have a key slot. In 7-1/2 years, I never noticed it, because I just unlocked all of the doors at once, and opened the ones I needed, never knowing they were never locked.
