It was a great ending and quite the cliffhanger. I remember it vividly, I might rewatch the DVD again - the last time I'd seen it I thought it was there
It's a shame TFB didn't pick up on it, using the magical starchild as a copout.
Or, for that matter, the fresh-out-of-ideas TV show from 1985, when they needed to find new direction and fast since copping "Dallas", "Knots Landing", and "Dynasty" was proving to be a mistake. It was obvious they were scrambling for ideas. Huge miss of an opportunity. But the TV show also suffered from a pitiful budget - I can't believe it had cost $1 million per episode when they were always reusing old effects, even from the previous episode. Maybe the cost of the sets, when spread out among the 19 episodes, added to the figure. Especially as the 84/85 show started so well, it losing its way (quickly with the needless death off Martin) only shows a conflux of factors were thrown in too quickly. The show deserved better, especially with the main actors (Badler, Englund, Grant, Ironside, Singer, etc) all doing a lot to pull the show. Especially Badler, her "Diana" was watchable no matter how badly an episode was written. Not because she's eye candy but because she knew how to play Diana compellingly and richly. Very good actress.

They did indeed send a message to "The Alliance" who were fighting The Visitors in the stars. There was also a cult dedicated to an entity called "Zon". He was the mortal enemy of The Leader. All of Zon's followers were hunted down and killed. Neither story arc was elaborated on.

Yes, originally the last scene is them trying to send a message to the Visitors' enemies and hope that they can transmit it and help them out. Julie does mention that they have to face the reality that help may never come and they have to completely rely on themselves. When they continued the story in Final Battle, it wasn't mentioned because Johnson had left.

Well yeah. That's the last scene. Of course KJ leaving changed the intended ending.