Origin and history

Alexander Lexington was a misfit but capable pilot for Sentinel Squad O*N*E, a department of the United States military that operated gigantic Sentinels in the use of protecting mutants.
Lexington himself was a mutant, but withheld his status from his teammates.  He eventually befriended another mutant pilot, Meld, who helped him keep his mutant status secret from their teammates.

Decimation

Lexington lost his mutant powers after M-Day, when the Scarlet Witch removed 90-98% of the mutant population's powers

Messiah Complex

Lexington eventually became captain of the Sentinel Squad O*N*E.  They continued to patrol and protect the mutant sanctuary at the Xavier Institute until the entire squad's sentinels were infected with nano-sentinels, microscopic machinery used to control the actions of others.  The sentinels went berserk and all pilots, including Lexington, were killed in the attack.

Powers and abilities

Alexander Lexington was a mutant who could generate and emit electricity from his body, which allowed him to discharge powerful electric blasts or manipulate machinery. 

He is in peak physical condition and received various amounts of training during his time with the military. 

As a pilot for Sentinel Squad O*N*E, he had heightened strength, size, and durability of the Sentinel exoskeleton and had a variety of weaponry and gadgets at his disposal, including laser rays, nets, and smoke bombs.  The Sentinel was also capable of flight via jets placed on the boots of the robot.