Bill, if you go to menue "measuring" you will see statusline on end of menue, it shows reason why motor stopped. YOu must look there immediatelly after stopping. Next switching on will clear all error codes. I think it will be overheating of ESC. Try to move it to air stream with red sticker exposed to fresh air stream.
Also be carefull because ESC can start again when it cools down.
The reason can be too high KV of the motor, you need something under 700. 5 cell will not work well, because motor must be able accelerate and I think 5cell will be too little. Or try 5 cells and pitch 6 or so.