2005 Chevy Colorado ECM computer problem, need help!

[gldidr]

We need help and don't know how to proceed.  2005 Chevy Colorado Vortec 3500 3.5L five-cylinder Crew Cab Z71.  It is a great truck with low mileage.  My wife was driving and lost power.  Diagnosed by Chevy as bad ECM.

 

Chevy says they cannot find a replacement, I guess in their system.  Says cannot use salvage yard. 

 

I Ordered one from fs1incdotcom programmed with our VIN, but I was not able to get it to work.  Key cycling procedure was never recognized.  Put my original ECM back in and at least it started.  The Dealer said it was not trustworthy to drive, that the problem would get worse.

 

Chevy dealer says it could order one from a site like that above, but would not guarantee the work.  So if it did not work we are out of luck.  The part is guaranteed but we cannot just throw away service charges if it does not work.

 

Fixed income and it is our only vehicle. 

 

Suggestions or part sources would be greatly appreciated.

 

Sorry for long post.