Don't be ridiculous.
Murder is defined as killing the other person.
Therefor the fact that he is not dead is an automatic defense since whatever you did does not fall under the definition of the crime. However the law on mischief defines mischief as destroying or altering or making unusable data on a computer. You have commited mischief if you have engaged in any of the activities listed by definition. It is so broad that someone who wants to get you does not really have to prove that what you did was unauthorised. He simply has to raise the question that perhaps you were not authorised, to get around the obvious stupidity of the law.