Help with my Roland D-50 please!!

[cristia...@gmail.com]

Hello everyone, I'm having a very strange problem with my Roland D-50, I turned it on today and I can't see any characters on the display, the display is lit, you can see the green light on the whole display but there's no characters, letters or anything. And weird thing is that the sounds are still there, if I change banks and patches you can hear all the different sounds even if I put in a card I can hear those sounds too. I just can't see which sound it's selected or anything at all. I've heard other people complaining about no display but also no sound, but I do get all the sounds so I really don't know what the problem is, any help would be appreciated