Astra engine wont start

An engine control malfunction is plausible. Is the check engine light on? Any unusual sounds when trying to start? Have you checked the battery cable connections for corrosion or looseness? The fuel injection system may be worth checking, but that's less likely with a complete non-start.

The engine light is on. What should I look for on the battery cable connections besides obvious corrosion?

Besides visible corrosion, make sure the terminals are tight. A multimeter can confirm voltage, but even with enough voltage, a poor connection can stop the starting current. Given the engine light and no start, and that you've checked fuel, I recommend a diagnostic scan at a workshop. ECU failures can have many causes, and professional equipment is needed to diagnose it.

It was the battery cable connections. Repair cost was 155€. Thanks for the help.