Red LED flashing


I’m new in APM and just receive and install a mini APM V3.1 board on my quad copter.
The firmware flashing id OK and the ESC calibration is also OK, the 4 motors are spinning after ESC calibration.

After powering the APM I have a fixed greed LED and blue and red flashing quickly. Then the red LED is flashing quite slowly and I can’t arm the motors.

Have you any idea of the meaning of the red flash and why i cannot arm the motors ?

Please provide tlogs and/or dataflash logs to help troubleshoot your issue.

Thank you,
The mistake was coming from me, i’m not familiar with the APM arming procedure. Now I can start and fly, the copter have strong oscillations on pitch and roll so i guess that i need to lower the gain.
I’m on APM Planner 2.0.18 and in the configuration tab i only have “basic tuning” and “standard params” but no PID menu.
Did I made another mistake ?