I have just experienced the same problem @ the Palm Beach Marriott.

My situation was a tad bit different in that my key worked, the light turned green and I was able to enter. (expected result!).

I stepped out of the room for a second and realized I had forgotten something and simply out of habit reached for the door and much to my surprise it opened... Hum.. a fluke? I tried again thinking maybe I didn't shut the door very well... Nope... Called the front desk and the response was "we'll send someone up." - Ok, no problem. Guy comes, says "Oh, we have this problem, the battery died. I will fix it right now."

HOLY CRAP! Seriously, he takes a screwdriver, undoes the bottom, puts in 4 AA batteries and says "You're good to go ma'am."

So first of all, what idiot designed that program - Dead battery should equal door LOCK, not UNLOCK. Secondly. I have to say, I was a bit upset at the front desks casual response. There wasn't even an apology... Debating where to take this now? Just never stay here again?