KERN ACJ120 - Display full of symbols at turning on

Dear LabWrench,

when I turn on my KERN ACJ 120 4M, the display shows all the symbols and remains in this state forever. If I unplug and re-plug the balance, it runs the check normally, then show "Off" on the display. If I turn it on it shows all the symbols again and is not responding if I press any button.

Thanks for your help,

Michele