History
Little is known about Professor X's life before the zombie plague arrived on Earth-2149, however, it can be presumed that it followed much the same path as Professor X of Earth-616.
A zombiefied Alpha Flight attacked the X-Mansion. Storm informs the X-Men during the battle that Alpha Flight has ripped Xavier to pieces. Cyclops, trying not to deal with the fact that Xavier is dead, continued to fight.[1]
A zombified Beast later informed Doctor Doom of Xavier's death, and that it was the zombified Reed Richards who reprogrammed Cerebro to seek out humans.[1]