Ok if the appliance isn't running at all then its more then likely the control board on the back at fault.
What you need to do to confirm is remove the plastic cover on the left side of the compressor and locate the black wire towards the top of it.
Then with a multimeter you need to check to see if theres 230v there. You will need it pluged in for about 10 mins before you test it.
If there isn't 230v there then its the control board at the top on the back at fault here. But if there is then its the compressor. But as you say its quite it means the fan inside the freezer isn't running and if there was power going to the comrepssor this fan will work as it comes on at the same time as the compressor itself.
But there is another control board inside the fridge at the top. Its behind the dial that you turn. But you tend to find if this is faulty it will get to cold in there. But worth checking the wires to it just in case.
But what we do on these is replace both the rear board and the temperature board inside the fridge as there isn't a way of testing them.
But if you just want to replace the one then go with the rear board as this is the part that usually fails and causes this fault.
Now in the past ive had them where its been turned off for a few hours and then turn back on and its come on. Its the relays that can stick so might be worth trying that if you can but I think you will find its going to be the rear board that's causing this fault here.
If you need anymore info just get back to me.
Ok when you first turn them on it will run an auto test so it does whirr for a few seconds but then just leave it about 10 mins and then it should kick in properly then.
Let me know what happens.
Ok if its intermittent stopping and starting as is the compressor then its looking like the rear control board at the back towards the top is the fault here im afraid.
Ok that's fine, Its looking like the control board is the fault here.