Pixhawk 4, motor beeping

I have BIG problem what I have try solve about 2 months.
Motor not work its only beeping about every 3 seconds. ESC and motor works fine with only receiver but when I connect it to pixhawk it only beeping.
If some knows how to solve this please help us. We cant do our flights to customer because of this.

Fixed wing setup:
One motor
Pixhawk 4

I think , can you calibrate your ESC ?
And min think is when plug your battery to your craft then motor beeping as a stating beep right ?? After this happening ?

What outputs are you connecting the ESC to on the FC?
If you are using the PM board shown, connect the I/O PMW from the FC to the FMU PWM out on the PM board and the FMU pins pn the PM will be the servo outputs.

Same issue, I have done the things which you had mentioned , enough the beeping is out. Hoping for help to resolve this issue.

When it beeps like that it means the ESC is not get the pulse signal from the FC.
There could be many reasons for this from hardware to setup of the FC.
It’s hard to help with the information you have provided.