F355 GTB 96 Alarm going off without reason when locked

Good afternoon everybody,

after 1.5 years of trouble-free motoring I have now some very annoying behavior of my F355 alarm/immobilizer.
I was driving the car for ca. 100km and parked it in front of a restaurant, and roughly 10min after the alarm went off without reason. By pressing the key fob, the alarm went off and the doors opened. The key fob and all functions still perfectly fine then....

After another 100km including 3 longer stops without alarm, I parked the car at home for a wash and again after ca. 10min the alarm went off without reason. Exactly same behavior as before.

I can say that there was for sure no vibrations/big noise emission when this happened.

I decided then to de-power the car for 30min and power it up again. Since then and now for a 30h, the alarm stayed calm.

The car is parked 500m away from my home in a building with restaurant/apartments with the battery charger on, so it would be super annoying this alarm would go off again....

Anybody had similar experiences?
Can it be that a "movement sensor" is maybe loose/damaged?
Being an alarm/immobilizer, there must be a backup battery somewhere which might be faulty, right?

Best regards, Simon

 

actually the alarm went off before the wash...

so it looks like I am not the first one experiencing this...