Pixhawk short beep problem

Hello guys,

I don’t know if it is appropriate to ask this problem here,
I try to connect my Pixhawk(APM:Copter V3.5.3 ,PX4V3) with my Raspberry Pi 3 and use Dronekit to control it.
However, when it start to takeoff, my pixhawk made some voice, it sounds like four short beep, after that, it automatically landing.

I check this Pixhawk sound, but there are no one matches.

Did I do something wrong? What’s that voice meaning?
I appreciate your advice, thx.

Here is the test video Test