Putting an audi a4 engine into passat

So i had a blown engine on a passat 2006 with
broken crank. But i found a cheap audi a4 2008
that crashed but good engine. Anyhow i was able
to swap engines with help of mechanic. Now that
everything is in place car cranks but does not have
any spark , anyhow would like help of anything that
i can do. Somebody told me if i also swap the
same ecu it would work but still with my doubts.
Anyhow hopefully somebody out there can help