Hi , I am trying to bring to life an older Clarion car cassette radio model PP-9217N. I am not sure if a security Code is required to start as all I get is a brighter led screen with no information when power is supplied. If a code is required what would be the procedure and how many digits ? No response to the power on push button or any other function. I was expecting the word code or similar on the screen. So I am not sure whether a code is applicable or if I should start trying to find some other electrical fault. Thanks for any advice....