Cliff the high resistance connection can be anywhere from the battery to the motor. It does not have to be a bad solder joint. My last incident was caused by the arming plug. It had been arcing a little more than normal and I was thinking about cleaning it, but decided to fly first. I too off and in my first down line I go to power up and I hear that squeal. By the way the problem normally shows itself when you are throttling up from a power off and in a vertical down line where the motor is spinning with out power and as you power up coming out of the down line, you hear the squeal. Just land and hope you have not damaged the ESC. My last one still worked but power was down, so I swapped it out and sent it to Castle for inspection/repair. They sent me a new one. Damaged beyond economic repair.
Is there anyone out there who knows how to check an installed system for the voltage drop and resistance that causes it, so we can identify when this situation may be identified before it happens?
Perhaps this is a good topic for another thread?