Leibherr CUNESF3503 Fridge not cooling

Hi

The alarm light on my Liebherr NoFrost Fridge Freezer is continuously flashing. The freezer is cold but the fridge is not.

Appliance Details:
– CUNESF3503 Index 20A / 147
– Service No 0982654-01

What I’ve attempted:
– Reading this forum it appears to likely caused by build up of ice on the evaporator
– I’ve turned off the appliance for 24 hours
– I’ve removed the back plate in the freezer and removed the ice that was building up on evaporator.
– From best I can tell the drain hole is clear
– The fan in the freezer is working.

However after the 24 hour defrost attempt, I am still not getting cooling in the fridge. The alarm light is still flashing.

I’m attempting to attach a picture of the freezer compartment (with the back plate removed)
https://ibb.co/WnMb76C