@independent:The cables are out of question, work on Android.

@Estel: Reinstalling is my very last option since everything else works fine. I was hoping to get to know the device a bit better by trying to find this fault.

I even can mount a USB flash drive using USB mode 1.0-2, so I do not think the connector is faulty either.

Could someone shed some light on how the flow of action upon USB connect is?
1.Somehow it is sensed if is a charger or data cable.-->This is not the problem with my device, since in /proc/driver/musb_hdrc both cahrger and datacable are recognized as such.
2.The popup is triggered, but not in my device. Can it be invoked manually?
3. The Popup button starts something, depending on selection. Are these by any chance the scripts under /usr/sbin such as osso-usb-mass-storage-enable.sh?

Can this whole process be gone through manually?

So if anybody knows some part of the puzzle, please dont hesitate to add it.

Thank you,
Enrico