I have hundreds of flights and I witnessed one fly-away by my brother that was caused by taking off prior to properly recording home location and not waiting for both series of rapid flashing green lights. In a case similar to yours, the phantom was brought back for a quick battery change and restarted. After takeoff I detected quickly that It was flying quickly away from my brother and asked him if he was full throttle forward. He said he was not and I took over the controller and flipped the controller into ATTI mode that does not use GPS. I then brought his bird back safely.
