The tip that helped me: check to make sure the black 'cup' around the eyepiece is pushed all the way down in place. If it's pushed up even just a little, the sensor in it causes the LCD to go blank.
Thank you, ScottyP!!! This issue happened to me over the summer, (and just fixed itself) and then again tonight. Didn't even know about the eyecup thing. Thought I was going to have to send it in for repair.
