Ford CD player needs code?

Hi, my battery died and now the Ford stereo needs a code. I have the code from the manual, but when I type it in, it has a countdown to 30 mins. At the end of this, it keeps asking for the code, and then another countdown. The model is 6000CD and the model no is M002114. The code I have been putting in is 7976. Thank you for your help.