How to fix Grundig Sound 4000 "safe" problem and input the code?

I have Grundig Sound 4000 radio and a code, but I can't find the way to input the code. On the screen it says "SAFE" and there is no response when I press the buttons... What should I do?
Your help would be much appreciated
Thanks.

P.S. Tried the "hold the AS button while turnig on the ingition...and so on..." thing, but it didn't work. Leaving the radio on now for 24, maybe that will help. Can the radio be locked in a way that it will not unlock anymore?