I'm sure you know the power button on the remote will turn the screen black, but leave the program running. I just found out that simply touching the screen while it's black will turn it back on.
Is the screen a dead black, or is it illuminated, but blank?
If the screen is black, but the power is on, try shining a flashlight at the screen and look close. These screens, like most other video screens, are LCD's, and have a back light. If the back light does not illuminate, you can still see what the image should be, but you have to look close, and a flashlight helps.
Unfortunately none of this helps directly, but perhaps knowing the answer to these questions will help someone else figure it out.