Motor not spinning issue

What ESCs are you using?
Where are your ESCs connected on the Pixhawk?
Did you calibrate RC and ESCs?
What happens when you test the motors in the Mission planner motor test page?

Do not disable arming checks! (especially not all of them!) They are there to catch mistakes before arming to prevent possible damage and injuries.

Also there’s some calibration missing that should have been done before, like IMU temp cal for example.

I recommend to read and follow the How to methodically tune (almost) any multicopter guide. Download the methodic configurator, edit each file in the configurator to suit your copter and write them to the FC one by one as you read along. The guide and configurator tell you what to do at any given time. Do not skip any steps! Anything that might seem like a shortcut will result in a worse tuned copter in the end.