Product review (3 stars): One outta Two
ordered two, one works great but the other is D.O.A.  Put the batteries from the working one into the non-working one...no change.  So it is not a battery related issue.  50% is not a very good return on my investment.

This is an update. I raised it from 2 stars to 3 because the D.O.A. just started working for some reason.
If it goes off again, I may commit assault on battery.