No I don't think you have to replace the keyboard.
Some questions:
1) Level fail alarm you get directly or during washing?
2) what is the water level shown on the screen?
3) what happens when you disconnect the hose from the Presto-state?
4) It is not a watchdog problem (alarm message when the level is not reached within the adjusted watchdog time)?
Best regards, Met vriendelijke groet, Mit freundlichem Gruss
Harry Schutte