Thanks for comments
The ambient room temp is about 14C and no different to before. The fridge/freezer mechanism seem OK and it works for an an hour or so each time I re-boot. Then it just stops - the light are still on and there is no alarm, just no heat exchange and the both fridge and freezer...
My Samsung Fridge freezer was working fine until 1 week ago when it suddenly defrosted and I had to throw out the contents. There was some excess ice which I removed but now when I turn it on it seems to work OK for several hours and then it just stops again and warms up.
Any ideas?