It's not just the batteries that need regular servicing, the pads do too. They expire on a similar timescale to the batteries but most AEDs don't alarm for expired pads.
It's not uncommon for AEDs to also need firmware updates, although this typically doesn't effect the usability of the device.
It's not uncommon for AEDs to also need firmware updates, although this typically doesn't effect the usability of the device.