@David-TP Tried a power supply from the other (working) unit and not change. If pressed for 1s it will do the flashing yellow (boot up phase) then go back to flashing green. I never see blue. I can...

@HelpFixDecoApp correct, followed those instructions and it completed without error.

I bought a 3 pack of AC1900's on ebay... well, I got a 3 pack of AC1200's instead and one was flashing green after doing a reset on it. The seller offered me a generous partial refund to keep them...