The Lawnmower Man / Lawnmower Man 2: Beyond Cyberspace

The Lawnmower Man (1992)
Scientist Lawrence Angelo conducts experiments on Jobe, a mentally challenged lawnmower man, using advanced computer technology combined with drugs. Lawrence immerses Jobe in virtual reality—a three-dimensional computer world. The scientist succeeds in developing the mental capabilities of yesterday's simpleton to the level of a genius. But the military secretly interferes with the experiment, and the subject transforms into a super-intelligent, psychopathic monster in human form, who then lays claim to world domination.

Lawnmower Man 2: Beyond Cyberspace (1996)
Jobe the lawnmower man did not perish in the flames but became an inhabitant of virtual reality and began working on creating a new computer system—a global network linking all computers in such a way that it would be impossible to escape from it. The insane Jobe tries to recreate the discovery of his "creator," scientist Benjamin Trace—a universal computer chip.