You do realize that the pack you have is only rated for 78 amps? On the MMM you should at least have packs capable of 100 amps continuous. I am not surprised the ESC blew on those. I would also not be surprised if the cells are now damaged as well.
QFT -- the MMM can draw upwards of 400amp surge, and 90-100 amps at full speed. You need a pack rated for 100A minimum.
Patrick del Castillo
President, Principle Engineer
Castle Creations