Reason (1): Usage of recycled / refurbished battery.
Solution: Use original FRx battery from authorized supplier. (The use of supplies i.e. pads and batteries and accessories that have not been tested and validated by Philips may damage the Philips devices themselves, and repair costs may not be covered by the Philips warranty. Read reference letter from Philips)
OR
Reason (2): Smart pad seal is broken due to customer misuse.
Solution: Replace pads and battery.
OR
Reason (3): Pad is not properly installed
Solution: Reconnect the AED pad
OR
Reason (4): AED pad peeled out from the case.
Solution: Replace the AED pad