We’re building an ROV based largely on the BlueROV2. It does not use BlueROV ESCs or thrusters however. For our setup, we need to edit the PWM whilst disarmed, e.g. from 1500 to 1450.
We have tried parameters including SERVO TRIM, adjusting MIN / MAX and various others. Whatever we changed, following reboots, it simply outputs 1500 for all channels 1-6. 7 & 8 work correctly for the camera servos.