I was carrying out a mapping mission with my H520 when I lost connection with the drone. Probably happened when the drone went out of sight beyond trees and my directional antenna was pointing the wrong way at the time. The drone wouldn't respond to pause or return-to-home commands, but just carried on with its pre-programmed flight. I tried re-connecting the camera but nothing happened. Eventually the drone returned home when its battery drained down (it was the first battery of a two-battery mission). So my query is - how do I regain control of the drone if connection is lost during a mapping mission?