The .DAT log is already attached in post #3
Then I think that motor have suffered from the crash ... this as the logs definitely show that something fishy is going on with the left rear ...
If we first look at the AC pitch, roll & yaw ... the movement that the
MA2 does at 90,5sec indicate the left rear, this as the roll goes negative, AC starts to lean to the left (green), it pitches nose up & positive (blue) & yaw CCW, meaning one of the CCW props/motors have lost rotation & no longer generate torque CW (either left rear or right front). As seen later after that the AC return the sudden movement but creeping back in the same pattern & hell break lose at approx 94sec ... the AC spiraling down. All this indicate a lost thrust from the left rear.
View attachment 103425
Then if we take a look att the motor RPM's. Again something happens at 90,5sec ... for all motors. But later on the rear left (light blue) clearly distinguish itself by only produce around 100rpm when all the other rev between 4000-7000rpm.
View attachment 103426
If we look at how the motors was commanded by the FC ... again we can see that the rear left (light blue) should rev to 100%, and all others much lower. This means that the FC want the rear left to rev faster to keep the control of the AC ... but the actual rpm's doesn't max out anyway as seen in the chart above.
View attachment 103427
Then a last check on the motor currents as a peak value there for any motor indicate that it's stuck. And again the rear left stands out with 4 times higher current draw then the others (purple).
View attachment 103428
All this together indicate that something happened the rear left motor at 90,5sec that got disastrous at approx 94sec when the rear left grinds to a halt & the AC starts to lose height in a spiraling motion.
If this is a warranty ..? Hard to say, if nothing obvious is found in the motor that comes from the AC itself (lose magnet for instance) it's hard to point on hardware failure, it can also have been some debris blown up from the take off spot that jammed the motor.