2003 A4 Cabriolet Lock Beeping (alarm on?)

2003 A4 Cabriolet Lock Beeping (alarm on?)
Good day, all. I am looking for a bit of insite on an issue that recently surfaced on my 2003 A4.

When I lock the vehicle, it begins beeping and does not stop until I either open a door and shut it, or unlock using the FOB, or Lock and Unlock with the FOB while opening various doors, etc.

I am at 53K miles and finally out of warranty. Therefore a cost of repair is stressful at this time in my life.

Does any one have any suggestions on how I might repair this myself or any insite on what this may cost at a dealership. I work in the Automotive Industry with interior electronic modules (body control modules, door zone modules, lift gate modules, FOBs, etc) and understand quite a bit about the electronics in vehicles. However, I have not had any experience with Audis and have taken it for granted that my vehicle works and that I need not to know the electronics behind functionalities.

Any assistance will be much appreciated.

Kind Regards
Lisa Kalinowski

Stick your head next to the rear nearside wheel arch, if the sound is coming from there then its going to be the alarm sounder unit that is in a cavity behind the boot lining on the nearside. They are known to develope problems and just beep at you! Not too expensive to replace, circa £100'ish from places like vagparts, just need to peel back the boot lining to get at it.