How can i fix my vauxhall astra vdo 500 radio?

Hi,
I have bought a 2003 vauxhall astra. The previous owner said the radio has not worked for a while, but just needs the security codes which you can get from any Vauxhall dealer (he give me some money to cover the cost of the codes)

I described the following fault to the vauxhall main franchise dealer by phone.

radio will not switch on, and not showing the "SAFE" display, so unable to start inputting the sercurity code (when I get one)

power is reaching the radio as red flashing security light works

I put a cd disc into the radio and it powered up, and displayed safe.

I then tried to put a security code into the radio in accordance with car's radio manual, It would not do step one of the process to input the code.

The radio as now powered down and not showing safe. CD will not eject as the radio has swithed off.

Vauxhall dealer said I need to buy a new radio off them, £300 please.

Can this radio be fixed, or do I have to buy a new one.

Thank you