No colour?

Hi guys,
Just wondering if I could get a little help with something…
My boyfriend has a ps2, a slimline silver version, and he said that he got it for Christmas last year…
I was playing it the other day, and all of a sudden the game lost all its colour. Everything else is fine, no problems with the sound, or any other aspects of the ps2… just the colour.
I tried restarting the console, and that didn’t work, so I took out the disc and cleaned it, and that still didn’t work, so I tried another game, and still nothing.
My boyfriend came in and then tried starting it up without any game in it, but it’s the actual console…
So does anyone have any ideas on what the problem is and how to fix it? We tried cleaning the laser and checked all the connections…