guys I am in the final step I do it all I calibrate all but when I push the throttle only 2 motors spin why? I have to bind again? or ii have to do something in my transmitter setup I got flysky i6 and APM 2.5 . I want 4 motors turn with same speed when I push throttle!
Technically, you don't want them all spinning the same speed
But check and make sure all solder joints are solid between the motors and the escs, If they have bullets make sure the connections are tight. Make sure your esc wires are plugged correctly into your flight controller, check all possible hardware failure points before you get into software possibilities
You could try swapping motors, and escs around to check for faulty hardware, but like @tylorwashere stated; the motors should not all spin at the same speed so that it will be stable in the air.
Recalibrate, I've had this problem several times, it happens when there is a problem in calibration and your throttle range is basically 0 or non-existent.