I tested the voltage/continuity for the can bus, the battery (for load and I recharged it), the battery terminals, all of the fuses, the starter, the ignition switch, the TRS, and the grounds. I think that's all, it is all very easy to test when you have a diagram like this for the ECU connector:

(https://charm.li/Saturn/2008/Aura%20...trol%20Module/) *My car is le5*.

I also DTC scanned to see if the ECU was the only computer not communicating which was conformed already with the initial u0100 code. After all of these tests, we were certain that it was the ECU. Bought a new one for about $100 on eBay that was programmed to vin, did the security key relearn, and the crankshaft position relearn with a friends dtc reader/programmer, and it started right up. However, it seems like I could've done it without the scanner, just by going through the protocol with the rpms, parking brake, a/c off, etc.

I am facing another challenge though that I posted about on the Saturn Aura thread on this website.