[Countdown to Destruction]

I think the Mellenium Message was sent by Zordon from the future. In the original timeline he watched all the Rangers and the rest of his allies die. Before the UAE destroyed themselves and the Galaxy from civil war...He sent a message through Blue Centurion so his past shelf would know what he had to do to prevent the future. He made sure it went to Dimitria because it was too dangerous to sent the Police Bot to Eltar with the war about to erupt. Its likely part of the message told Zordon that he had to sacrifice himself to save everyone. So in the new timeline Zordon dies making sure his Rangers don't.