This thread is to help anyone who may be experiencing similar situations and a potential fix.

Recently did a minor rebuild on my d16y8 and turbo'd it, currently running an AEM EMS series 2 PNP. I could not get the ECU to power up. Connected my factory ECU, that one didnt power up either. Suspected poor battery charge as with the key on, the dash lights were weak and the vehicle could not crank, just one solid click from the starter solenoid. charged and checked battery, voltage good. Main relay functioning properly. Cable tightness and integrity good. voltage to starter and wire resistance/voltage drop good - no issues found. Adjusted the heavy ground strap from the transmission to chassis to another chassis grounding point - issue fixed. DONT OVERLOOK THE SIMPLY STUFF was my lesson....

Hopefully this may help someone, even though it seems obvious I know, but the symptoms may lead people down the wrong path as it did for me. We always want it to be something complicated....

 

Not to mention the main ground near the thermostat area. Thats the ground for the ECU