Would you kindly check the model number please, I dont have that one listed>
OK on this model there is no thermostat it is controlled by electronic sensors feeding information back to a central control pcb in the top facia area. First question is does your version have a fan in the top of the fridge and is it spinning when you open the door (there are two versions of this model one with one without)
OK thank you can you tell me what settings you have on the freezer display, temperature wise?
OK let me explain how it all works and then you can make an educated decision. Simplified you have two cooled areas, the fridge compartment and the freezer compartment. Refrigerant is passed into each seperate compartment via a two-way valve at the back which is controlled by the electronic pcb at the front. This pcb measures the temperature using electronic sensors called thermistors whos resistance value changes dependent upon temperature. The most usual faults with these is either -
a. The valve burns out.
b. The pcb is faulty or
c. One or more of the sensors fails.
In order, usually if you have a look at the electronic board on top of the valve you can see if it has burnt out, however to replace this you need to be a refrigeration engineers as the pipes have to be cut, a new valve brazed in and then recharged with refrigerant. The PCB is just a direct replacement, one out on in (usually there is no sign of damage). Finally you can check the sensors out with a multimeter if you have one but these are the most reliable of the components. You biggest issue is do you have the tools to do it and can you get the parts even if you do.
OK if you take the pcb out you will see a white block on the right hand side with either 6 or 8 small cables connected - rather than the other side which has larger cables - the resistance (remember this is dependent on temperature) should be around 2K ohms. You can test them out individually and if you have one that is faulty it will show up as open circuit or a dead short.
Are you shoving the probes in the back of the connector, its sometimes difficult to get them to connect. But you really need something out of the third one - kindly recheck.
OK next thing is to check the valve on the back but thats a job for when you have time, not an easy job if you havent done it too often.
Mark up the valve cables, you will have to remove the cover to do this. Check the pcb for damage, Once you have these checked see if you are getting a voltage at the cable ends.
If you could that would be great - then just come back to me when you're ready to go again.