Pat,

    The 4 holes are for taking the radio out.  Take 2 pieces of heavy guage
wire (a coat hanger) and cut them about 4 inches long.  Bend them into  "U"
shapes and force them into the holes - both sides at the same time.  The Radio
will pop loose and you can pull it out.

   Can't help you with the code. If it wont accept the code, talk to the
dealer.

R Gunter