cannot reset Accenta 8ep471a keypad?

I live in a first-floor flat and in the early hours today my alarm went off 3 times, even though the system was unset, and each time I entered my code to turn it off. After the last time, at 5.30 am, nothing is now showing on the LCD keypad, other than a top row of blacked-out square. I cannot reset the keypad to show date and time etc., no matter what I try. I have turned off and removed the plug to the main control box but the keypad is still powered with the power and day lights still on. Can you assist please?