so picture is super dark and OSD shows up as a black box?
easy fixes to try, turn up the "screen" control on the high voltage "flyback" transformer. not a lot, but see if turning it up a bit causes the screen to go gray. or the image to brighten up some to see what's gone on in the OSD.
me thinks the ABL circuit is defective causing the dark picture. it could be a simple as a shorted diode.
it could be something as complicated as a blown out video amplifier. hard to say without actually seeing some pictures or something.