Have you checked power cord and also determined there is voltage at receptacle. from you description it sound like there's no power to fridge, do the door lights work, if not there's no power to fridge, could be bad plug or cord if outlet has power. Have you checked the thermostat to make sure it is on. Also the defrost timer you put in could be in defrost sequence, did you try to advance it. you do not provide enough info other than fridge wont start so these can be the only logical solutions. I fans are running and compressor won't start then its the compressor switch. I hope this helps cause there is not much more it could be. There can be other reasons but this is what fits your question.