After 2 years, my charger cable with a NEMA 50 plug, began running very hot at the plug all the way to the cable's LED display. Too hot to touch! I called electrician, who replaced the NEMA 50 outlet and the 50 A dual breaker. Plug and cable still runs very hot, and worse, the max charging current is <32 A, which comes out to 19 mph. There is a "poor grid quality" message in the display and warning that charge rate has been reduced. Still shows 244 volts. Do I have a defective cable?