I recently built my first racing quadcopter and second drone. I used the build guide found here. I had a good first flight but on my second flight a had a crash and one of the motors gave off a lot of smoke. I tried to fly it again a couple of times and then gave up and came in to check on the motor. The coils on it were black so I ordered in a replacement and wired it up. Once I wired the replacement and tested it gave off smoke as well. I think something happened to the ESC during the crash. I wanted to check here before I buy another ESC just in case it could be something else. I am also wondering why the ESC stopped working and what I did wrong.