Amstrad GX 4000 Display problem

Hello,

When I turn on my Amstrad GX 4000 the power light comes on but I get no sound at all and it displays a stationary green tinted black screen, it has squares in places on the screen like a interfered breaking up image on a digital box for a tv. all the connectors on the game cartridges are clean and ok. I have had a look in side, all the capacitor and etc. no leakage from the caps no obvious blown resistors or voltage regulator and sign of blown or tampered with components within the console on the mother board?

Any advice would be much appreciated