Blaupunkt car 300 (E) code?

Hi

I recently bought a car but the stereo just beeps a red light in code.
Can you please help me, find out the code for me.
Stereo is Blaupunkt 300 (E).
7648852320
GH0300H8548434
90533422
8635132851

Please also let me know how to enter it to unlock the stereo.

Cheers

John