Vice City problem - no video

[Armitage56]

Hey,

I've been playing a backup of vice city for a couple of weeks now.
I recently moved my ps2 to an other room and now vice city doesn't work any more. All I get is the ps2 logo when the disk starts, then the screen goes blue but I can still hear the audio.
Other backup games still work.

I tried the following to fix this problem:

-Opend the ps2 case to see if al wires were still attached. Some wires were loose, so I brought it to a guy who could fix it.
-Made a backup of the 1st VC backup

None of this worked, so perhapse someone here knows how to fix this problem?

I use a messiah mod-chip.