Fridge keeps freezing
Can't solve your problem, but just to report we have exactly the same issue, a huge block of ice forms on the upper rear panel. The compressor seems to be running 24h, not matter where the 'thermostat' is set.
I suspect that there was/are a faulty batch of thermostats. Or (since there is no metal cooling plate to bolt it to) that the T/Stat probe has somehow come adrift from its correct sensing area and is not correctly sensing the temperature inside the fridge.
If I get to the bottom of the problem, I will re-post here.