Many things here : Esc burnt... TX batteries not sanded ??? No rx glitch capacitors ? No fan on esc with gearing too high for the drivetrain friction...Maybe dendrites on motor timing board(happens to old novak motors)...Motor timing too high...Runtime too long(reduce to less than six minutes)...Drivetrain bearings catching when heated or pinching inside tight hubs....Radio bec overloaded too fast..lipo connectors no good...etc.....