The system you refer to is based around a Eurosec CPX control panel. The no. you give relates to the keypad itself. Intelligent system, checks control panel battery hourly to confirm it is in good order. Keypad would normally indicate fuse/battery fault if it detects a fault. Would agree control panel backup battery probably needs replaced. Battery will be found in main alarm control box, a blank plastic box probably hidden in cupboard adjacent to electricity consumer unit.
Should be possible to locate engineer manual online. Be aware that engineer code will probably have been changed by installer. They have the option to lock this in and can only be reset by the code used by the installer. That said you may not need the engineer code simply to change the battery, using your code or fob to stop the noise when you open the main box.
Alan
August 2022
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