I don't have a Lagoon but here are some alarms that could sound on my Saba 50 with engine & generator off:

- automatic bilge pump activation
- Engine control panel is energized, but engines are off
- low battery state-of-charge or low battery voltage
- Carbon monoxide detected
- anchor alarm set on chartplotter and boat has gone outside the radius setpoint (there are numerous other alarms that can be set on the chartplotter)
- AIS proximity alarm triggered
- Radar proximity alarm triggered
- Man Overboard button pressed on chartplotter
- Digital Selective Calling message received on VHF
- Chartplotter has lost communication with Autopilot