Blow up the main breaker

I have the this same model electric Kenmore 80 Series I changed the upper thermo swicth then I turn on and heat it for few moments and then suddenly the wire plug make a short circuit and after verifyng one wire apparently loose it and contact the other fase one, now I change the plug for a new one, but the dryers do no heat it and check it and the thermo switch have continuity and so on heat element. are the any other reason for this happen or could be there any failure which provocate this short circuit which never before happening, I check the blue and violet conector which come from the fabric type switch (the center oen of the three small ones) with a blue resistor but I don´t remenber if the violet going up near the other violet cable or next the blue one a one side. Any idea ?