I've had to disable the Pre-ARM checks on my APM (Y6 f/w 3.0.1) because it will not arm.
The confusing part is that it won't say *why* it doesn't arm.
I have Mission Planner running, via 3DR telemetry, and the obvious causes do report on the screen on the first arm attempt. (No GPS lock, etc).
With full GPS lock, all systems calibrated, and everything ready to go, it stays Disarmed. The screen does not show a reason for the failure to ARM.
If I disable the pre-ARM checks, then it does ARM and fly correctly in Stable/AltHold/Loiter.
Is there any way to discern from the logs or other data why the Pre-ARM check is failing?