Cannot turn off alarm

[dynoiasi]

Hello,

I have a strange problem regarding the alarm system in my Mazda CX-7 2008, EU version, keyless entry (card type).
At the moment I am not going to focus on why the alarm sometimes goes off when I normally unlock the car via the keyless entry button on the door, while having the entry card with me. This happened a few times, not often, and I have yet to find a pattern when this false trigger occurs.
My biggest problem, which is also strange, is that once triggered in this way I cannot stop the alarm from sounding. I can start the engine, either with or without the mechanical key, I can lock/unlock normally the car via the remote, I tried all sorts of things and the key is definitely correctly recognized, everything works ok but the alarm buzzer sounds every 10 seconds.
The only solution I have found to turn the buzzing off is to remove the battery power for a while and then reconnect.
There's some strange design there to keep the alarm condition after the key is correctly recognized and the engine can be started. However I wonder if anyone else has the same problem and, eventually, a solution.

Thank you very much for your time,
Florin

[SSinstaller]

Probably time for a new BCM.

[dynoiasi]

That's a possibility, although at the moment I am still hoping for a happier ending of this....
In the meantime I had the chance to connect a tester to the vehicle. The only DTC's I found in memory which might be relevant were on the GEM module:

B1318 - Battery volage too low and
U0100 - Lost communication with the PCM

Also there was a "Lost communication with the PCM" on the 4x4 module.

I don't know whether these are to be concerned about or are simply caused by low voltage on cranking or even appeared when I disconnected the battery to stop the alarm... I guess I'll have to poll on DTC's some more on these modules. And of course, there's also the fact that I did not scan with a professional Mazda tester, but a general Launch X341 with very old software...

Anyway, the good news is no DTC's on the PCM and BCM on this 40.000 miles vehicle. I'll post here if I find anything else on this, thanks!