***This post contains BATMAN V. SUPERMAN spoilers. You've been warned.***
Well, it's not a device that is the result of the Transformers' AllSpark and Marvel's Tesseract hooking up for a night and it's called the Mother Box. This was confirmed by director Zack Snyder in an interview with Entertainment Weekly.
"That’s the first glimpse of the Mother Box there. It was an agonizing birth."
This incarnation of Cyborg, in the DC Extended Universe, has his origin story clearly seen in the LexCorp video file. Snyder discussed it with EW:
"I really wanted to show Cyborg’s birth because I feel like he plays such a strong part coming up, and I really wanted to give a sense of him. I really want [the audience] to know how far he’s come."
The how and why Cyborg is a mere man of his former self remains to be seen and it could be revealed in JUSTICE LEAGUE or the solo CYBORG movie further down the road.
But it's that Mother Box that non-comic book readers are probably unfamiliar with. In a nutshell, it's an alien supercomputer device used by a race of higher beings called New Gods. It has a vast array of abilities and powers while attaching itself to a host to grant special powers to him/her.
This is also device used by Darkseid, who is hinted at coming to Earth at the end of BATMAN V. SUPERMAN and in a recently released deleted scene (see post link below).
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