S80 audible alarm going off
 

Hello, all!
Recently encountered my audible alarm sounding after lock down. No breach of entry observed in any of the occasions. 2001; S80 2.9L, non-turbo. No visual alarm, (headlights, horn etc.) merely the small "wailer" alarm. Any suggestions on the source of the problem? Is this a DIY project?
Thank you, my fellow Volvo enthusiasts!
Gene
Hammond, IN