So we know the RCM is OK.
We know the ECU is OK (as per Rob).

Now, if you leave the key "ON" for 45 seconds, does the engine fan warp up to high speed? I can't find where you mentioned a yes/no to that question.
If the fan speeds up, that points to the ECU somehow not getting what it needs. If it does not, that points to what I call "an interlock issue".