Quad Falling like a Leaf - Unknown Reason

Myself and others tested our ‘quadcopter’ (vtol quadplane with wings taken off and reflashed firmware) and we had a weird crash happen. The quad yawed, then started to decend (which is what it was supposed to do), but then started to spin uncontrtollabley about the three axes, falling like a leaf. Gladly, our pilot was able to save it at the last second but the reason for the falling remains unknown. Myself and my team are relativley new to all of this and can’t seem to diagnose the problem on our own, any help / ideas would be appreciated:
We have noticed at around 17:00 there was a yaw commanded, and then all of our noise on all of our sensors seems to double or triple. Our best theory is that a motor mount came loose, but we are unsure. Thanks in advance for the help!

From the log, vibration is still dangerous even in normal flight.