My RZ42PX11 Has Coloured Noise But Audio Is OK?

My RZ42PX11 Has Coloured Noise But Audio Is OK It was working fine, we switched it off and an hour later when we went to turn it back on all we get is coloured noise on the screen but sound seems ok, can't access anything not even the menu :( only 3 years old, we were told it would probably last 12 years plus, paid £1800 for it......what can we do