The smoke alarm saga (cont.):
So, yesterday it starts beeping again. My wife finds 2 9V bats that are both corroded as heck. So, I'm off to CVS to buy a 4 pack ($23). Replace the battery again (I figured the one I used was dead also). Fine, but the bat door won't close, whatever.
This morning around 0400 it starts beeping again. I read a bit on line and notice the bat door is supposed to be closed, I order a new smoke alarm. Old one still beeping. After my wife gets up, I try again to close the bat door, and force it closed. No more beeping. Yay. Order cancelled.
I had to really push the little door to get it closed, anyway, you might encounter this issue some day.