Remember how Samukai wanted Dr Julian 2 build war machines 4 him? Maybe, when Zane was born, his mother died from childbirth, then Zane died afterwards. Dr Julian must have gambled with Samukai, lord of the underworld, 2 get his son's soul back. Somehow, he channeled Zane's soul into a computer code, then downloaded him in2 the robot (sorry, NINDROID). Anyways, Dr Julian must've owed samukai, so when he died, samukai revived him just 2 have Dr Julian repay him and build the war machines (which attacked Kai's blacksmith shop [and kidnapped Nya}).