Car Alarms: Alarm siren too quiet., police siren, celica gt

Question
1991 Celica GT, Black Widow aftermarket car alarm. I went out to drive my car a few days ago and the chirping/siren is now very quiet. So quiet that there is no way it would stop a thief. It was not raining, and I find it odd that the ground could be damaged while the car is just sitting there. Also, when the alarm is triggered now, the siren makes an assortment of noises (sounds like a firetruck), whereas it used to only make a police siren sounding one. Any help would be appreciated, Thanks.

Answer
2 things come to mind. It's water logged, dry it out completely
and it will eventually restore. 2. the ground wire is
either loose or gone on the siren. Check this first.

But the siren changing sounds? That's a new one on me.
Take it to a local stereo car alarm shop for
inspection if no joy to have him look it over.

let me know what you discover.

ALARMTEK