According to the Assyrian King List [/riao/KingLists/AssyrianKingList/AssyrianKingList/index.html#AssurRabi], Enlil-nāṣir son of Aššur-rabi I, removed his brother Aššur-nādin-aḫḫē I from the throne and ruled Assyria for six years. No inscriptions of Enlil-nāṣir II have been found.
Yehonatan Hershkovitz
Yehonatan Hershkovitz, 'Enlil-nāṣir II', RIA 1: Inscriptions from the Origins of Assyria to Arik-dīn-ili, The RIA Project, 2024 [http://oracc.org/OldAssyrianPeriod/Mittanianhegemony/Enlil-nasirII/]