Well, I would disagree that there is some mystery regarding this tragedy. Completely understandable providing he knew the folks in the adjacent cabin and they let him in. He forgot his room card, who hasn't done that at least a dozen times? Typical 16 year old, bullet proof, that's the way I was once upon a time. He gets onto the adjacent balcony and decides he will just climb around onto his own balcony. He would enjoy the risk.
Heck, one time our balcony door slammed shut and locked when I was out there. I was thinking that if one of the neighbors showed up I would climb onto their balcony and go down to the desk and get a new key card. Yea, I know, they could have just called and got someone to come open my cabin, but I was figuring on "conquering the challenge", why? Because it was there.