Patient complains to Doctor: "It hurts when I do this"
Doctor replies: "Then stop doing it"...
Sooooooo... Stop pushing top right of LCD screen.

Seriously I also previously experienced an LCD outage and with Gary's help and a flashlight we determined it was the bulbs. If you can see a display with a flashlight, then it indeed is the bulbs, or loose solder joints, or in your case perhaps a loose ribbon cable, In my case the display was fixed along with a motherboard replacement through Yamaha.

Good luck...hope it keeps on a workin'