I don't get it either, I made it as a trash parody on How to clips, with lots of embeded text, and not much real info on surface.
However, there is all the info needed to find it online and enter key code, should you need one.
it happens when you have to change the batteery. Radio ask for a code, and if you don't have original booklet, or have that No. writteen down somewhere ....
you can follow links from my clip to download decoder, then type in the code. Or ask me in comment below the clip. I will gladly calculate it for you.
What I don't give and what is the hardest part, ... you have to know serial of the radio, so decoder would have something to decode. If you're out of booklet, you have to pull the radio out and reaad the serial from the sticker on the back. Pulling the radio out is the hardest part. I think I mention all that in the embeded text, but frankly, I've forgott what I'wrote there.