1992 W124 Radio goes dead

[justme300e]

I have a weird issue with a newly aquired 92 W124. It has the original radio. 1st when I turned on the radio it flashed "wait" for about an hour.Then the word "code" appeared.I entered the code from the Mercedes benz code card included in the MB sales packet. Then the face plate just goes dead. I disconnect the cars battery and re-connect and the word"code" appears.I enter the code again and the radio goes dead again.Can any one help me with this issue? thanks in advance!