Accenta G4 Alarm Keypad display showing black squares?

My Accenta/optima alarm keypad display is just showing black squares, if you look from an angle then you can see the text.
We had a power cut yesterday morning and when the power came back on the display screen was like this. If you look from the sign you can back the wording out and the alarm still works when I set or unset it. People reported hearing a very loud bang in the area as the electricity went off. Any help would be great, thanks