One of my four ESCs burnt out on a first test flight of a new quad build. I plugged the battery in, armed the drone, and one of the motors spun for less than a second before stopping. I immediately saw white smoke and smelled burning plastic. This all happened with the throttle set to idle. The other three motors are working fine even under load.
I opened the ESC to take a look, and sure enough, one of the FETs shows signs of burn damage. This same motor was operating correctly and responsive on the test bench, without a prop. I also noticed that this ESC gets very hot to the touch - 80C maybe - even when disarmed (but powered).
What could be the cause? Is a bad ESC likely? I'm wondering if it's a short, but the fact that it was responsive on the bench makes it seem unlikely.
30A Simonk ESC