Greetings Paul !
I downloaded the manual and viewed a picture of your unit and it appears from my observation that this unit utilizes a 'flourescent display'. I have seen these types of displays fail more than once, although usually it doesn't usually happen abruptly. Usually when they fail they simply get dimmer and dimmer until you can no longer see anything displayed. Has your display just stopped working abruptly or did it fail gradually as I have described ?