SMEG FAB32QNE fridge section not cooling.

I’ve got a SMEG FAB32QNE which seems to have developed a fault after a power cut. The fridge section doesn’t get cold any more but the freezer is working fine. I’ve looked into it and found it’s got 2 compressors so it’s basically two systems – a separate fridge and freezer. I tried switching off the freezer section to see if the fridge compressor was running. I can hear the hissing sound of the gas in the back panel of the fridge section like normal so seems the fridge compressor is running but the fridge is not getting cold. Any ideas or help will be much appreciated. Thank you.