Coolant Migration and ECU

So the mechanic gave me a diag last week with a list of problems(posted on an earlier thread) and also said my car exerienced coolant migration.
 
He says coolant is forced through the wiring harness into the ECU and into the Instrument Panel. I had him show me the connection to the ECU and I see a slight greenish residue on the 2 connectors the CTS harness is connected to. He adds my ECU is damaged and probably should get my instrument panel replaced. Is there a way to know for sure my ECU is damaged? And how would I go about replacing it?
 
Has anyone experienced this before?

I remember reading about this at one point, when it happened to someone else.  I don't recall the specifics or what the fix ended up being, but if you search for something along the lines of "coolant migration ecu" in the Search feature above, you may find that post/thread.