2013 27" iMac display suddenly blue with white vertical lines and can't see anything (different to the black screen problem I've read about on the web). Anyone else have this problem?

My 2013 27" iMac display has died! Now all I see is a blue screen with white vertical lines and can't see anything else (different to the black screen problem I've read about on the web). Anyone else have this problem? Any help appreciated... I've called AppleCare and as it's 5 months out of warranty they"re not interested!