what is wrong with my nissan radio???

Pleeeeeeeeease help! I have a P reg nissan. The battery recently died and I don't know if it is connected to this but the radio is now broken. When I turn it on, the screen light comes on but that is it. No text is visible on screen (but this has been broken for years) and there is no sound. The cassette is not working either. I've tried inputting the code but had no success.

Thanks in advance :)