As a non-expert but a frequent follower on this subject, I'm pretty sure failed modules are pretty rare, and when replacement "works" it's almost always because the R&R fixed a bad connection.

Reminds me a of a story from a corporate computer tech who, back in the lated 80's, needed to keep fleet of office PC's running. When a problem proved elusive on site, the machine was "carried in" to a local authorized repair station, and would return functioning fine, for awhile, anyway.

In a flash of inspiration, she unplugged a problem machine and, instead of carting it off, she banged it on the desk, plugged everything back in, and, voila! Running like new!

That became the new procedure. It often worked. She dubbed it a "simulated carry-in." LOL!

Later, she added re-seating all the internal plugs and boards, knowing that's what the repair guys were usually doing, anyway.

 

Turns out we need a bcm and not an ecm got the car back for now while we track down the part sorry for the confusion

 

Is this guy giving a money back guarantee that the ECM is the problem? More likely a bad wire. Still no evidence?