360 AC ECU replacement procedure

As background, the heat in my 360 doesn't work, and the previous owner took it to Ferrari Scottsdale for troubleshooting. I have the service report wherein the tech did a few tests and determined that the AC ECU is not responding when heat is requested. The part was backordered and the customer didn't want to wait, so it was never repaired.

Fast forward 3 years and I want the heat to work so I bought an AC ECU from an exotic recycler off ebay. I plugged this ECU in (left the old one in its bracket), and the new one doesn't work at all. No air/zero response from anything on the AC controls. Plugged the old one back in and everything works again but no heat still.

I can only find one part number for this part, so I assume it being from a 2001 Spider and going into my 2004 Modena shouldn't have any compatibility issues.

Is there something else I should be doing? Does the AC ECU rely on being bolted into the bracket to ground itself?

 

There are a couple of grounds provided by the wiring in the harnesses. Seems odd that nothing would work. Isn't the ECU case plastic anyway?

There are no HVAC system wiring differences between Modenas and Spiders. Sounds like you got a dud.

 

Yes, plastic case. I'll check with the seller and see if he can exchange with another one. If not I guess I'll crack this one open and do some exploring.