What is a Mother Box? Glad you asked. Read what wikipedia has to say in full, but here's a snippet:
"Created by Apokoliptian scientist Himon using the mysterious Element X, they are generally thought to be sentient, miniaturized, portable supercomputers, although their true nature and origins are unknown. They possess wondrous powers and abilities not understood even by their users, the gods of New Genesis. These range from teleportation (they can summon Boom Tubes) to energy manipulation. Mother Boxes have been seen healing the injured, including Darkseid himself, after he was beaten by Doomsday. Metron stated that each Mother Box shares "a mystical rapport with nature". They provide their owner with unconditional love and self-destruct when their owner dies.
Mother Boxes have sacrificed themselves for causes they have believed in and are greatly respected by the people of New Genesis. In physical appearance they are most often in the shape of a small box, but they can also be much larger (as is the one carried by the Forever People), and do not always need to be in the shape of a box at all (Mr. Miracle had Mother Box circuitry woven into the hood of his costume). They usually communicate with a repetitive "ping!" which can be understood by their users."
Does this not sound like the 4s iPhone?
The concept of the Mother Box is Jack Kirby's. What a fantastic imagination he had.