It's actually hard to say. I know that usual clicking sound when it switched over to battery before but this time around it is something like a very faint click if that makes sense. I would say it isn't even trying to switch over.Does it sound like it's trying to switch over? Mine does not want to switch back to AC, I can hear the relay clicking but it just dors not stay on AC.
So yours is the other way around (ie doesn't switch back to AC) ?