the main relay went out, replaced it with a new one, car ran fine,

What is your question?

drove the car that evening for about 25 miles, it shut off. started it and drove about 2 miles it shut off again, wouldnt start back up. checked the new main relay that i had installed and it was supper hot, couldnt touch it, the car had to be towed. what would cause a brand new main relay to heat up and burn out that quick ?