radio help AX

[bad driver]

Hi, I have a rather rubbish AX as a runabout, Ive put the code in the radio wrong and now it wont let me re do it. I only entered it wrong twice as well!! Ive tried leaving it on for over 4 hours continuous but still locked out, I know the BND button is sometimes a bit iffy, does anyone know how to do some kind of master reset on it as disconnecting the battery doesnt work.