A sorcery can't be put onto the battlefield and a permanent can't transform into a sorcery. If an effect exiles Summon: Esper Maduin and then instructs you to return it to the battlefield, it remains face up in exile (unless that effect instructs you to put it onto the battlefield transformed, in which case it returns as Summon: Esper Maduin). If an effect instructs you to transform Summon: Esper Maduin, the instruction is ignored.