DeLonghi Perfecta ESAM 5400.S EX.1 affiche esc et

Hello,

I have a DeLonghi Perfecta ESAM 5400.S EX.1 it only displays the two ESC and OK lights next to the two lower left and right buttons.
If I press one of the two buttons, nothing happens.
During the diagnostic test:
- the screen displays all the icons for 1 second.
- The power button displays the ECO mode.
- The temperature button turns the grinder on.
- The two-cup button turns the block up and down.
- The steam button injects hot water through the brewer to the two coffee outlets instead of the milk nozzle.

Despite the reinstallation, the machine is still out of order, and both ESC and OK lights are blinking as always.

Please help me to find the solution.

Thank you very much.