[Help] VTOL plane crash

Hello,

We are testing the Y4 type VTOL by adding one rear motor in Tricopter.
We had a crash while conducting the hovering test in QLOITER mode.
At first, the roll, yaw, and pitch control were good.
However, the aircraft crashed as it suddenly heard the motor turn off.

and And when I did log analysis,
Just before the crash, motor1 and motor2 signals bounced in reverse, followed by a pilot signal.

We uses 12S by connecting two 6S batteries in series.
Before the test, only one 6S battery was removed and plugged in due to an EMI error.
Can this be a problem?

I don’t know what the cause is. Please help me.

Here’s the flight log.
Thank you very much for your help.

https://drive.google.com/file/d/1BDM73Msd2yG2uFt5OYiEZcNCZKEvz_bw/view?usp=sharing

Um… I use it to help others in the future.

The problem was simply the disconnection of the ESC Signal wire.
It was confirmed that a disconnection occurred in the ESC of Motor2, which caused it to crash while tilting in the direction of Motor2.

While browsing the forum for Y4+1 (if anyone has done it) i saw your post and reviewed your log. As i can see you have Q Frame Class 7 and Q Frame Type set to zero(which means plus).

Wiki States: The default configuration is X. If you want one of the arms to serve as the exclusive front-facing direction, select the Plus configuration. For tricopters, traditional helis and Y6s, the frame type is ignored.

Which means you would need Y4 which so far i can see its not supported in the code for Vtol