What does the 4 digit display show when you turn on the BS1? It should be 4 flashing squares that prompt you to enter the PIN.
You select the numbers with the Wind and Rewind Keys on the back of the device and use "Store" to proceed to the next digit.
When the pin is accepted the display should show the selected radio station or CD track.
In case your entered the wrong PIN more then three times.
There is the possibility of getting a master code but the procedure is rather complicated. Your local B&O dealer has to request the code
from Denmark. The master code is then sent via mail back to your dealer. So, you see it might take some time.