radio

I had to change the battery on my 98 intergra gs and now the radio does not work. I can not find the owners manual. I got the dealer to give me the code and he said all as I have to do is punch in the code. When I punch in the code on the radio I still get the error message of err 3. Does anyone have any clue as to how to get my radio to work again. Thanks for any help.

Can you locate the radio serial number online from the audio dealer for a 96 Acura TL