Designed to drive HEI module plate...

have since blown up two HEI modules. Both have been complete failures following otherwise normal operation. Once was within 5 minutes of a cold start while running, the other was about 30 minutes after moving the car from one driveway spot to another on a cold start. South Florida weather ensures that none of this ever takes place at less than 55 degrees Fahrenheit (at worst).

Is it possible you are mounting the modules upside down, thus not contacting the heat sink area of the module?