Help! C4 Radio Code Problem
 

I have the Blaupunkt Reno 2 Radio in my '90 964 C4. Long story short....when the battery dies as we all know, the radio security code must be entered to allow use of the radio. Being as the previous owner took the code card out of the manual....I headed to the Porsche Dealership. Result, they cannot retrieve the code from the radio as they usually can. The dealers computer locks the radio when they try. What can I do from here??? The dealer tells me the codes on the back of the Blaupunkt as very different from the normal ones they see. He is calling some local special radio shops, but nothing yet. Thanks