Grundig-Database for your serial:
"GM0303S4053239
05/01/95
1659"
did you enter the keycode correctly??
maybe check the serial
or try it here -> http://forum.eserviceinfo.com/viewforum.php?f=8&sid=062c1af724b7be5548c11d03f0df1cfd
telebumm007, December 2010