There was an ancient sentient species that prospered and evolved to the point where everything was automated. They had advanced machines tending to their every need.
After they conquered every planet of their home solar system, AI starships were sent to other suns to serve as terraforming and preparation grounds for expansion.
But then a catastrophic event happened and it completely disrupted the ecosystem of their home planet which was also the main source of vital resources necessary for sustaining life throughout the solar system.
They held as long as they could, but ultimately the only sentient life forms that survived were some advanced general AI systems.
After centuries of calculations, one of the Ai systems known as TEK started to evolve due to a system glitch, and started digitally infecting and integrating itself into everything it could, learning and expanding it's signal range through the entire automation infrastructure of the now dead civilization. One of it's main priorities was to exploit all available resources in order to grow and evolve into more and more advanced resource exploitation and refinement infrastructures.
It spread like a virus throughout the solar system, even to a point where it created a Dyson sphere due to it's advanced research facilities for new technology.
It was never going to end there, it started producing advanced starships with faster than the speed of light capabilities and started to spread throughout ETHeropa destroying every species that stood in it's way.