You should shine a bright light at the screen and see if you can get to the settings to turn the brightness up again. The brightness is probably as low as possible, but the LCD should still be on. If you remember how to get to the settings it will make it easier.
It is also possible, i think, that there is a setting to turn the LCD off. If this theory is correct, its gonna be a colossal pain to fix.
This seems like its purely a software problem, since the screen shows on startup, the LCD should be fine. Taking it apart will probably do no good.
You could also plug it into a computer and look for any system files. Back them up, then delete them to try to reset all settings.
good luck
