No arm apm pro with no safety switch

Hello. My friend purchased a apm pro with no arm switch and buzzer and he has problems getting the motors to start.
The controller does not seam to send any signals to esc.
Esc calibration works fine and there is no problems with motors in Esc calibration. But after that the Esc send weird signals and do not work even after forced arm (with all safety check disabled).
MP motors test end with “command rejected by mav”.
It looks like a safety switch not engaged but there is no safety switch on the controller and I can not find the parameter to disable it.