Polar 115 E - turn on but no image at display only back light turn on

More details, We found the battery in CP2 discharged. It was replaced.
The machine turn on, the backlight for the display turn on but no image appears.
The KC2 is ok. It turns on and the red led is flashing slowly (1 Hz) but have no comunication with CP2.
In the turn on process you can hear one beep, but the three beeps are not present to indicate the communication between KC2 and CP2.
Neither the backgauge can be activated although the frequenz inverter is ready to job. (green led blinking).
It seems like the communication between CP2 and others cards is not established, but maybe you can give more guides to fix the origin of this failure. it will be usefull.
we wait any comment
thank you in advance

 

Control the graetz bridges on the control board