Samsung RL36SBMS Bottom Freezer problem?

Samsung RL36SBMS Bottom Freezer. The problem is that the fridge and freezer have stopped cooling altogether. The electricity is getting to the appliance, the light is on and a low humming noise (fan maybe motor?) can be heard. But there is no drop in temperature however long the appliance is left on.

Can u help pls:
1. What is the likely cause or troubleshooting?
2. I have removed the back inspection panel and there seem to be almost no parts to replace - certainly no fuses I can see?

Look forward to your advice. Cheers and thanks in anticipation.