wow!! Its really sad to see that. Such an expensive/wanted little plant, only to succumb to heat/shipping stress. i hope that it can comeback, but considering the stem is going black and such a plant generally doesn't have a great root system..... well.... all u can do is hope for the best.
But don't sweat it man. **** happens! You just got to move on. Now you know that these plants require a lot more TLC.
I hope you can get something figured out for this.