w203 faults

hi folks

could someone help me out with this problem ... i havnt got round to fixing the last problem and ive another

cd radio is showing up as -------- lights are on the radio but no sound its like its frozen up


my other problem is the passenger side door lock its 'machine gunning' i was told is the correct phrase for this problem .. it just goes up and down and makes a grinding nose... been told i need a new door lock for this.. i was just wondering if anyone had a 'how to ' on this instructions and pictures on how to replaced the door lock

thanks

delboy