300A screen printer control panel shows "--"how to fix it?

300A screen printer control panel shows "--"how to fix it?

As the picture shows:

The control panel shows "--"

and alarm with sound;

Check the air in or not;

As the picture shows;

The blue ring is the fast switch;

Move to right is open;

Move to left is close;

Make sure the air is in, then turn on the power;