The flash of the SONE-220 creates a temporal loop. The photo Kael saw at the start wasn't of his death; it was of the moment he transcended time. The "dead body" was a decoy/duplicate created by the device's reality-warping. Kael disappears, leaving the empty camera behind. Vesper retrieves the SONE-220, but the memory card is blank.
Vesper looks at the camera, triumphant. The SONE-220
Kael meets a rogue physicist, Dr. Aris, who explains that the SONE-220 creates a self-fulfilling prophecy. To fix the timeline, the device must be destroyed, but the corporation wants to mass-produce it to control stock markets and wars. The flash of the SONE-220 creates a temporal loop