If while you were taking your turbo manifold and stuff off, if you hit your wrench on the alternator post, you need to check your fusible links.
Thats the only thing i can think of that you could have done during a turbo change.
If it just soo happens that it doesnt want to start check your clutch switch to make sure its being depressed all the way, check the connections to the starter and battery and so on.
Im gonna guess fusible link though.