I would definitely call Amazon. Since the Fire is serialized they may have a way to remote wipe it. It's at least worth a shot.
Did you happen to buy a Square Trade warranty? I remember reading on Amazon where a guy dropped his Fire in a lake and Square Trade replaced it.
http://www.amazon.com/review/R3747PY..._res_rtr_alt_7
I believe there are still some honest people in the world and hopefully someone has found it and will turn it in.