I do not have any experience with those coded radios, sorry. I stick with the old analog cassette radios!! But someone here should know.

If you have the manual and the code, you should be able to do a RESET using a paper clip. Can you look at the radio and look for a pin hole? If the faceplate is removable, remove it and look for it. This assumes there are no blown fuses, and the battery is fully charged.

Have you checked all the radio fuses?