Auto Mode mission copter all motors sudden stop and crash

Hello all,

While I was trying an autonomous mission (which I had tried 20+ times before and succeeded) this time I had a fatal issue. The copter just fell off from the sky. It had almost reached the last waypoint but then all the motors were cutoff. The logging also stopped so the crash or the fall wasn’t recorded.

Could someone please help, I’m really in need of help right now. I thought that it might be a battery issue, but couldn’t really deduce what happened.

P.S: It was a windy flight at almost 20 km/h speed but this copter has seen more than 35.