It kind of depends on the facts and your jurisdiction. With the button, maybe? With a death note book, almost certainly not.
When proving the elements of attempted murder (or any non-statutory crime), the state has to prove both "mens rea" and "actus rea" (that you intended to do the thing and that you tried to do the thing), but when you're being charged for something "attempted" you have the defense of "impossibility," when the actions you are trying to take couldn't have possibly worked.
Now, that doesn't cover cases where you were only wrong in point of fact. For instance, buying fake drugs from a cop. But it does cover instances like using a voodoo doll.
There's more detail on all the above in the illustrated guide to law, which is a pretty solid resource for stuff like this. Here are the relevant sections:
Actus Rea Explanation: https://lawcomic.net/guide/?p=261
Attempted Crimes: https://lawcomic.net/guide/?p=344
Impossibly Defense: https://lawcomic.net/guide/?p=416
Probably, but if you're interpreting user inputs as raw code, you've got much much worse problems going on, lol.