That said, given you’re specifically trying to simulate failures, you should be able to achieve an equivalent result by just disabling the output for the motor you want to “fail”. You can do that by setting the relevant SERVOn_FUNCTION parameter from Motor{n} to Disabled (0), which you can either set in QGC, or set directly with MAVLink (e.g. using a Pymavlink script). If you have a separate MAVLink endpoint set up for it you can even use a pymavlink script while QGroundControl is connected to the standard endpoint (e.g. to simulate a sudden live failure).
Insert thruster failure. Create a node that makes a thruster fail in a predetermined point of time.
Info: https://discuss.bluerobotics.com/t/is-it-possible-to-adapt-at-runtime-the-motors-contribution-to-the-6dof/13079/3