hi new here just got a second hand punto it has a blaupunkt san remo cd 31 radio in it my problem is i have no control of headunit nowt happens when i push buttons when i turn car on unit lights up but just shows 0.00 what i take is the clock for it goes up as i drive but goes back to all zero every time i switch car off do i need a code as previous owner had just put new battery in or is the unit broken