The ***** *****ghts at the top flash when the unit is generally in a state where the temperature is to high, if the fridge freezer isnt cold this would support this fact.
How cold is the fridge currently?
The freezer should be -16 or below, so it may be sitting at -8 freezing food but above the critical point the fridge freezer is operating to.
I would certainly start from a 48 hour defrost, and if it continues to have problems then start looking at the thermostats and control board. The majority of issues like this are resolved through a long (48 hours) defrost, as you often find there is a build up of ice behind the back compartment which stops coolant circulating around the freezer and fridge.