8596 Error code EE?

The above FF, shows error code EE , it also fails to start up unless it has been left off for 24 hours.
If you force to start, by switching on from the mains with the fridge door open, it will run for 5 minutes, the temperature starts to drop, then cuts out.
EE usualy means faulty defrost heater, have changed that and both thermal fuses along with frezer evaporator thermister.
If left off for 24 hours will then run for ages, with EE showing.
What next please ?