ahh the cool mac classic II.. I've got one of those.... nice little machine! I would take the logic board out and check for leaking capacitors/ bad solder joints. I have fixed many old macs by checking those.... also just be sure, the screen brightness is just not turned all the way down is it? For some odd reason I once had an old mac plus I presumd dead, but it turned out the brightness just wasn't turned up
If all of the above fails, you may have yourself a dead analog board... then if thats the case you mind as well make a fishtank!