UPDATE:
YES! I found the Root Cause !!!!
The problem was at the multi-connector in the trunks left side (where the jack is). I saw another thread with the same issue, that suggested this could be the reason.
Cause & Effect:
The hose that leads water from the sunroof (i believe it is), had slipped up from the air vent 'drainage hole'.
This caused the water to flood the deep left side of the trunk and cover the multi-connector. The combination of electrical current and water, is pure poison for such a connector and in effect, the wires and pins was completely deteriorated. Actually some of the wires just fell apart!!
For the moment, I have just pulled apart the connector and made sure none of the broken wires shortcuts. But it's an easy fix to clean cut the wires and replace the connector. This is something even I can do ;-)
Result: The fault is GONE!!
Thank Lord for this forum, that has such a wealth of money-saving tips, tricks and hints
Special thanks goes to Justin, for taking time to answer me personally on email
I will make sure to update this thread with a picture of the bugger.
I would recommend everyone, to take a look in this area now and then, since the hose easily can slip away and the longterm effect can be horrific (also from a body corrosion perspective).
/Lars