Upon Macarius' death Maximus became bishop of Jerusalem, and was present in 335 at the first synod of Tyre, and signed that council's condemnation of Athanasius.
Socrates Scholasticus recorded that Maximus "restored communion and rank" to Athanasius, Athanasius receiving support against the Arians and Maximus advancing the desire of the bishops of Jerusalem to have their see be equal in status to the metropolitan see of Caesarea, a desire later achieved in 451 AD.
Sozomen and Socrates say that Maximus had been deposed in favor of Cyril by Acacius of Caesarea and Patrophilus of Scythopolis, both Arians.
Regardless of how the succession came about, Cyril and Acacius would become bitter enemies during the next few years, disagreeing both in the Arian controversy and in terms of the precedence and rights of each see.
Eastern Orthodox Liturgics Wikipedia also notes his Universal and therefore main feast as August 26.