Assuming the Battery charger has failed as well, causing the BAT discharge - Any equipment that is powered by the switch/hot battery bus will fail.
What nobody has mentioned is that the fire protection is powered by it.
You will get the detection as this is powered by the battery bus but zero protection due to no hot batt bus.
The battery is your get out of jail card if your having a bad day, depending on where you are, I think a divert would be a good idea.