Flip at takeoff - arducopter only

Hi,

I am building a Tarot 690 frame hexacopter. My drone flies by default on px4 with QGC, flashing APM on the same setup flips backward at takeoff. Could this be the channel 2 reverted issue I am reading around the web about? If it flies on px4 I guess I can eliminate the motor direction, reverted props and all the other issues that can cause this, no?
I would also like to ask if there is anyway of trying the axes before you actually lift? I roughed up my drone pretty bad in a takeoff flip on rough terrain these days, a bit afraid to run more tests, not a lot of grass where I live and I only have carbon props.

check your prop rotations and rc input directions