Dead battery- what could it be?

[MikeMcMo]

New development for anybody still following!

Used my pal's charger to bring the battery back to life. When connected, I immediately heard a clicking from the passenger side in the car, and it sounded like a relay or a door lock constantly locking and unlocking, once every 1 to 4 seconds at irregular intervals, whether the key was in the ignition or not, whether the car was running or not.

Today I had time to try again, and re-connected the battery, then started pulling fuses. The clicking stopped when I pulled out E4, which controls the passenger seatback switch. I put the fuse back in and then moved the seatback forward and back and the clicking stopped. Great! But what caused it? I don't know. And what would keep it from happening again at random? I don't know.

I had the seats out 2 winters ago to put L-seat seat covers on and may have missed something when putting things back together, thought the seats have worked fine since. I guess I have to pull that seat and snoop around. Too bad electricals are a bigger weak spot for me than all my other weak spots. Anybody have an clues?