Radio not working?

Hi
I have rover 25 with a Rover R770 radio.

The numbers on the label on the side are as follows
22DC 594/60B
9022 215 94601
m/ch 118870

On the side casing is a stamped number in the metal,
RG594FX1118982.

When i switch on the unit lights up and there is the sound of power reaching the speakers.
I assume its just a code it needs, although this model doesnt have a display screen.

Just the preset buttons and search etc and a cassette player.