Hoping to get some more insight on this issue.

Problem is, once my vehicle has been started (1989 Camaro 1227165 ECM $6E APYP bin I burned myself) if you shut it off, it won't restart. Problem started very intermittent, gradually getting to the point of 100% repeatability.
When the engine is initially started, it will run as long as you like, with no problem. No matter if it is run 2 seconds or 1 hour, it will not restart.

I've followed the GM troubleshooting manual for crank no run. There is no injector pulse while the engine cranks, but there is spark and fuel of course.

One of the tests I've got a slight bit of a problem with "Is engine RPM shown during cranking?". My autoxray XP240 has NEVER to my knowledge shown cranking RPM. I've tried all the various settings (VIN F vs 8, Camaro, Corvette) and it still never shows engine RPM while cranking. Running yes. It fails the test to briefly apply 12 volts to the distributor 4 pin connector (pin C on the dist. connector or B5 on the ECM) which should show RPM on the scanner. Repeated that test for every VIN/app that seemed applicable just in case, and also swapped the ECM with a 1987 one that was running the vehicle previously, again does not show cranking RPM.

When the wire was given 12 volts (momentarily, with test light connected as directed) I could hear what sounded like the fuel pump and perhaps the IAC working, which indicated to me the ECM WAS getting a signal, regardless of what the scanner was showing. I'm baffled as to whether this is an autoxray issue or just something going wrong and it's showing that.

Dist. circuit was tested as described, it's not open or shorted, only remedy left is supposed to be the ECM replacement, which I'm not quite sure of since two previously ones good no longer work.

I've checked all the ECM connections, they all seem tight and good, and grounds are all excellent.

FWIW, the coil, distributor module, cap, rotor, plugs, and pretty much anything else you can think of, are new AC Delco pieces. (not swapped solely to solve this problem, changed out due to age/condition of original ones on the motor)

It's pretty obvious to me that the ECM isn't grounding the injectors. However, is that because of the ECM, or it not getting the signal it needs??

Any help or ideas would be appreciated.

Edit for finality: replaced the ECM, problem gone. Swapped out the stock injectors for Ford 24#, turns out two of the stock injectors were bad. Perhaps those somehow screwed with the ECM's, since I lost two ECM's back to back.