Beeping alarm speaker.
 

Hello all.
I have a 1999 A6 1.8T SE Auto estate, which has been off the road for over a year while I work on fixing various mechanical problems, and the now dead dash display.
A while back we had an electrical storm and all the windows opened getting the interior wet. Since then the doors locked and un locked them selves, windows went up and down and the battery died. Now dried out and a new battery it's all ok except for the following:

There is a very faint bleep coming from the alarm speaker, and the battery is slowly discharging.
I have had a look under the passenger carpet, and all around the box of electrics but I have not moved or unhooked it as it is bone dry and no evidence of it getting wet at all. :confused:
So I'm now thinking it maybe a door sensor possibly in the tail gate, as water has come from there.
Can someone please let me now where the sensor is in the tailgate, and how to get to it.

I would appreciate any advice you can give, thanks. :)

I have now found that the alarm siren does not work, everything else that is supposed to happen when the alarm goes off does. I locked my self in and moved about until the alarm was triggered.
Can I just pull the fuse for the alarm and run the car ok without the alarm?