That is actually really interesting that it would trip the phase inductance check: gimbal motors are usually driven in a different way than regular brushless motors, because of their higher resistance.
Actually you should have tripped the ERROR_PHASE_RESISTANCE_OUT_OF_RANGE first, but I just discovered a bug in that test which means it will never trip (it cannot detect resistances higher than 0.1ohm in the way it's implemented currently, and the trip level is set to 0.2 ohms). I will fix this bug.
Because gimbal motors have way more turns they also have higher inductance, and since the resistance test was broken, you tripped the inductance test instead.
"Gimbal motor mode" would consist of bypassing the current controller and applying the required torque by applying a q axis voltage directly, derived from the motor resistance and the kv value of the gimbal motor. In this mode, only resistance measurement is required.
I will add an issue on github for the gimbal control mode. If anyone here knows how to do this exactly then feel free to do it. If not, I can do this as soon as I have finished shipping out the kits.