whirlpool S20D not working

hi
I have the following American style fridge freezer, S20D RSB33-A/G with service codes 858615815010 & 110535006317.
Its all been working fine then this weekend I noticed the freezer had began to defrost. The front display was flashing freezer temperature and the beep, which I cancelled with the ok button. The following morning it was still flashing freezer temperature, the two lines –.
I removed the lower rear panel, switched it back on and the central fan was working and the compressor was warm/hot. There was quite a build up of fluff everywhere, so I unplugged it and vacuumed the general lower areas where ever the nozzle would reach.
I then plugged it back in, the door display goes through its normal checking sequence then displays whatever temperature you dial in for fridge and freezer, 6th sense lights and no alarm
however the freezer is not at temperature and when you look around the back neither the central fan or compressor are working
I left it like this for over an hour to see if anything worked but nothing. I have had a good luck around to see if I disturbed anything whilst vacuuming but nothing obvious.
Could someone please suggest where I should start diagnose.
thanks in advance