Ford Explorer Anti-theft problem

My 2005 Explorer Sport Trac will not start. It appears to be locked out on a continually cycling anti-theft module. No interior lights, constant relay chatter. I had to disconnect the horn to maintain my sanity. Neither key fob made a difference. Disconnected the battery, but that didn't reset it. Did replace the battery but the problem didn't surface for a week. Did notice the needles on the gauges were pulsating below the printed ranges. Any ideas as what to check before I tow the problem to the dealer?

have you tried to open the door with the key and then turning on the ignition? (bypasses the key fob to turn off the alarm)