OP, ignore all the PPs on this thread. They clearly haven't read your update.
Did you say your loathsome worm got a mere SIX out of a possible TEN? Hanging's too good for him, obvs. But as your basic starter, smash every screen in the house (an obvious distraction!), don't feed him for a week. Make him stay up all night practising next weeks spellings (this humiliation can NOT under circs be repeated) and repeating this weeks ones as well.
Disinherit.
Put him up for adoption, maybe? That might be extreme, but worth considering.
Or, you could just read this post over and over again:
Best thing I learnt when DD was around 10, was to stop rewarding achievement and reward effort instead. Same for punishment - although I've never actually punished as such, but have made her redo work or spend longer next time if I thought she hadn't worked hard enough and then didn't do well on a test etc.
as it summarises all the points beautifully, IMHO
It's all about the effort for me these days. DD can do very well sometimes with little effort and I tend to play down those achievements just telling her well done. But if I've seen her work hard for something then more much praise comes her way. She is now 13 and luckily is pretty self motivated. She wants to do well, so she knows that if she doesn't work hard she won't get the results she wants.