Tailsitter quadplane motors stoped and it crashed after EFK3 IMUs (0 & 1) emergency yaw reset in QAUTOTUNE

After yaw autotuning in QAUTOTUNE mode, while testing new PIDs for a quadplane tailsitter without controlling surfaces, the motors stoped, it crashed (fortunately near to the ground) and the only message that apeared in Mission Planner was “EKF3 IMU0 emergency yaw reset” and “EKF3 IMU1 emergency yaw reset”. We was trying to analyse the log, but IWe’re not finding why it happened. The board is Matek H743-mini running Arduplane 4.2.1 and attached to this post are the params used and the flight log.

Any help to find out what happened is welcome.

crash.param (24.1 KB)
Flight Log

looks to me that you lost a motor or esc…out3/4 were max’d, 2 neutral and 1 at min and QTUN.ThO throttle was increasing demand rapidly trying to stop the alt loss, but motors were max’d…that indicates that thrust was not being produced…the yaw reset occurred due to loss of control…not the issue IMHO

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Thank you so much @hwurzburg , we have reviewed the log with your notes and the temperatures of the ESCs reach just 125ºC (one reaches 126ºC). According to another comment we’ve found on the forum https://discuss.ardupilot.org/t/esc-telemetry-temperature/69094/3, it seems that most of the ESC’s MCU, in this case it’s a 4in1 Holybro Tekko32 F4 Metal 65A; when it reaches about 120ºC, they shutdown and reboot. The RPMs of all ESCs go down at the same time and we think it makes sense.