If you remove the battery,
then connect the USB cable,
The blackberry will not start, instead, it will display an icon which tells you to inserert the battery - and, the load will not see any device.
However, when I then inserted the battery, the loader recognized a Blackberry with an "unknown" pin, and then I was able to load the OS.

Wether or not your suggestion was meant to work like this, it *worked* finally.

Thank you.