HELP! WALKERA QR 350 Pro went bad, then gone!

[pax1980]

Hi, I've had a really sad day when I lost my Walkera QR 350 Pro, Gimbal, Ilook, with Devo-10 and RX-LCD 7 "display.

The first 2 flights today was successful take-offs and landings as normal. We flew pretty low taking pcitures.
The first trip I landed manually, the second trip I landed via GPS mode go home.
It had spent about 10-12 min of battery so far this day.

On the third trip it began to behave strangely and suddenly began to go against WEST / SOUTH WEST. It was as if the remote control gave minimal response (just strange!), and I really struggled to try to take it back.
When I realized I was about to lose all control, I put it in GO HOME mode. This gave no response.

The Walkera then went very fast WEST - WEST / SOUTH and rose higher and higher.
My co-pilot ran as fast as he could as he looked at the screen (wifi, rx-lcd)
It was not possible to see the drone, so the only thing he saw was the video signal.
The signal became weaker and weaker, but we recognize some of the area (camera was facing down)

We've been out searching for 6-7 hours in the hope of finding it, or pick up a video signal, but have not found anything.

I know none of you are psychic ... But does anyone know what could have happened? Has anyone had a similar experience? Are there any clues to what it might have done after we lost it?

Map on google map: https://mapsengine.google.com/map/edit?mid=zr5610uzmXxI.kne4CWbQ0Tuc[/IMG640]