Its definately not the screen, as changing the mk4 with another one, fixes the problem. It happened when I thought it would be a good ideas to brush off the dust on the circuit board!

I did notice something yesterday, when I lowered the brightness to the lowest setting, it didn't make a difference, until the unit rebooted and it had made the screen so dark, I could just about find the settings to brighten it back up.

I have changed the lcd quite a few times, but never noticed any adjustments behind it, will look out for that. Don't think it will make a difference to this situation though