Mopar ecm issues. Why wont they work?

Ok folks. The stock mopar ecm on the 80 apsen leaked it’s ooze all over the place. It still worked! Ordered a new one from rock auto. A standard (red/white box). Installed. Wouldnt work. I know people complain about the aftermarket ones so I figured it was just a bad one. Yesterday went to Napa. Got one of theirs. Started car today with no problem with the old one. Installed the Napa one…nope. Nothing. I had a third new one that I bought for the d100 project. Another standard one. Same thing. Nothing. But the original one works. Figured maybe a grounding issue. Ran a separate ground right to the battery and put the grounding star washers under it. Nope. Still nothing. So what’s the story? What should I be doing?