I am a newbie, so forgive me if I state the obvious. Do the other motors behave normally? If you haven't tried that, maybe you could secure the drone to the ground and test the power settings with it tethered. I looked up the HS 110D on eBay and found them for as low as $38 including shipping. If no easy fix for it, perhaps it would make a nice parts drone for a newer working one? Just a thought.