I have the same problem which seems to be common. I had the radio stripped today and the repairer thinks it is the driver chip, which he can't identify! Even if he could it is a surface mount device so very difficult to replace. I have just bought a £3.75 'fix-it' on E-bay. I have my doubts, but if it works I'll let you know where it came from. You can enter the code even with the display not working as I had to do this today. If your code is, for instance, 2345, press button 1 twice, button 2 three times, button 3 four times, button 4 five times then press and hold button 5 until the radio works.
Paul Saunders (paulwsaunders@hotmail.com)
December 2007