Why havn't I got display on my Fiat/Philips radio cassette?

I have just had a new clutch fitted which involved disconnecting the battery. When i drove home I found the "Fiat" radio was not working and the display was blank regardless of what I tried. Have checked fuses in fuse panel and at rear of radio and both ok. Checked and there is power to the radio but still no display. Any ideas what may have caused this problem through just having the clutch replaced? Without the display I cannot enter the security code. Is there anything in the radio I can do to fix the problem?