Radio code entry problem

[David]

We had the battery disconnected for service on our 1996 850 turbo wagon,
but when we entered the code in for the radio, it did not come on!
It just sits there with the code number in the display. I tried deliberately
locking myself out , then doing the 2 hour wait thing and re-entering the
code. Nada.

One thing we know, we bought the car used, and the person we bought the
car from said that the radio had been replaced in 1997, and so had a new
security code, which she gave us along with the old code. (When I enter the
new code, it is accepted, i.e. I don't get an EEEE message.

Any help?