I've had 2 flyaways, both with stock controllers.
The first one was a couple of weeks ago. 3.14fw, damn near landed, just a few feet from me, then it lurched forward into a bush, for no reason. Would not fly after this, just had constant flashing orange light. Connected it up the P.C, which showed that the controller was not working at all. Took the top off the phantom, tried re-binding it, no joy, it would never bind. Sent it back to the supplier, they agreed it had gone faulty.
Replacement arrived on 3.12fw, flew lovely, then about a week ago it took off from my garden in gps mode, just like many times before. This time though I saw a flash of red, as well as green as it took off. I nudged the stick forward just a tad, at which point it just kept going forward. So I tried going upwards nothing, it was like 20 foot off the ground, going forwards. No inputs worked. In a panic I hoped it had recorded a home point, so turned the controller off....Made no difference....So turned it back on, no difference. It was now out of sight and gone for good, together with a GoPro3 B.E, in its waterproof case.
Struggled to get my head round this for a day or so, but ended up buying a complete new kit....But this time I've also bought a Garmin GTU10, which I set up last night....Fingers crossed I might have half a chance of finding this one.