ORIGINAL: shassing
I am having similar problems. My a-10 took flight (brushless) but the canopy fell off during some inverted flight then I lost control 5 min into the flight (don't know if a motor failed or it was a transmitter problem) and it came down like a rock. I had another problem with a brand new F-16 esc catching fire before I ever flew it. I have had radio silence from Nitro Planes, no new esc. I guess we get what we pay for. Go to a local hobby shop where you can actually talk to a person and get some support. No matter how much cheaper these planes are, if you have to replace them weekly the savings quickly go away.
Shassing
PM'ing John is the best way to get your ESC replaced.
That you were 5 minutes into the flight, and saw a failure while inverted, may have been due to the ESC's voltage cutoff kicking in.
The ESC's purposely cut the motor when they hit the cutoff voltage. You can restore short term operation by bringing the throttle all the way down, and then back up. This restarts the motor.
However when the motor cut occurs, you need to land the plane NOW, as you basically only have enough power for a straight in decending landing approach.
All of this is by design and not a problem.