my kk board goes to armed but after 5 sec it goes back to safe . It goes from armed to safe in 5 sec(all 4 motors are working fine individually) i did everything i could tried calibrating motors one by one and all help me please (im using kk board 2.1.5, flysky fs-i6 transimeter and fs-ia6 reciver)

Hi Sacred!
Welcome to the forum!
We'll you aren't doing anything wrong!
The KK flight controller and most of the other flight controller out there have a built in safety feature. After arming if there is no throttle input detected then the board automatically disarms itself.

So I would suggest once you've armed the board kindly give 10% to 15% throttle and take off!

Regards,
Mohammed Naveed