Re: "re-verifying flight software code"
It’s worse.
They cut and pasted their own code, from the capsule to the service module, but then didn’t update what lookup tables it used.
If not spotted and rushed patched, when the two parts separated, the service module would have used completely wrong thrust, then try to self correct using even more incorrect thrust and so on until it’s out of thrust or has crashed back into the capsule.
Boeing sent multiple, untested, unvalidated software patches, written on the fly to the star liner whilst on mission, just to get it to return safely and it still failed to reach the iss.
The approach and docking at the iss hasn’t been tested.
Let’s not forget this was a proof it all works mission. That without direct intervention would have resulted in total loss.