Nova Igniter (Big Sigma Series, Book 6‪)‬

When you've lived a life like his, the last thing you want is for history to repeat itself. Lex has teamed up with mad engineers, clashed with technology-obsessed terrorists, and faced murderous robot hordes. He's even traveled through time. He has skills no one in history has ever had. He'll need them. Devastating cyber-attacks are targeting him. His closest allies are nowhere to be found. Ominous threats from his past seem to be leaking back onto his life. With the help of an off-kilter ship AI and his ex, Lex will have to get to the bottom of it all. If he doesn't, the galaxy's days are numbered.