During a normal flight with my P2, using a Taranis controller, it had red & green lights on normally, when it started a return to home run, completely out of my control. No big deal, but I wanted to land it myself, and get the camera angle right. My controller was 100% unresponsive, so I turned it off, then back on. At which point one of the motors did a full reversal. It tumbled down to a very hard landing, ruining the shell. After replacing the shell (and one of the ESCs) I got it all back together, re-calibrated, but one of the motors still spins the wrong way. Any idea what could possibly cause this, and how do I fix it? Many thanks!