I use QGroundControl and a Pixhawk Mini. I did calibrate all sensors and behind all Sensors is the green lite.
But when I try to arm the motors the message “Critical: Preflight checks failed” arise. How can I see what exactly the problem is?
Most probably this happens because of a connected USB Cable or Power Supply Issues.
Check your CBRK-Setting in the Parameters. Have you connected a Power Board and set valid Parameters? Any additional Messages in QGC?
What Firmware Level do you have - newer Versions should give more verbose Information than just “Preflight Check failed”.