Was it a game some other kid taught him that went horribly wrong?

Did he think, with child-like innocence, that he was going to be with Jesus and just wanted to get to Heaven as fast as he could, in the same way that any kid wants to cut to the front of the line at an amusement park?

Was he trying to escape a temporary problem but didn't grasp the grief it would cause his family?

Or, like teenagers and adults, did he mostly understand the consequences of his actions to himself and others and was so bothered by depression or other things that he did it anyways?

I'm betting on one of the first three.

I'm hoping for #2, that is the most benign and most easy-to-fix/prevent reason.