2010 1.3 diesel won't crank had ECM rebuild

[Ste_valves]

Hey all, got a 2010 Corsa 1.3 diesel that won't crank. Computer won't connect automatically, so there's communication problems. After input of vin, there seems to be all sorts of communication errors with alot of things saying no communication with ECM. I've searched the car for damaged cables, checked fuses/relays, went through wiring diagrams with no luck. Had ECM rebuilt with no luck (due to visible water damage on ECM board) the company assured me they tested the ECM on their test car and it worked fine after they repaired it. So ruling that out, I'm not sure where to go next. Any ideas? Thank you