Okay so this is the rough storyline that I think the Digital Haunt is about, but since there's obviously still puzzle pieces missing it's not complete and also I'm too lazy to add in the song references.
(Also I will refer to the main character as Sparkles* even though it's not sure it's him.)
So basically Cassandra speaks to Sparkles* in his dream/mind. She helps him sing (possibly his lungs are not working properly) and in return he helps her escape from the Echoplane. She is rebelling against it, is possibly going to be executed? and has to flee.
In the process of Cassandra escaping the Echoplane is destroyed by Cassandra but she is very severely hurt, she falls into Sparkles*' arms and they watch the explosion together in safety. Sparkles* is horrified over this but it was Cassandra's intention and she didn't tell him. Sparkles* feels betrayed but when he looks into her eyes he knows that he has to save her because he is still in love with her.
So he places her in a cryotic frozen state whilst he works on saving her, questioning his feelings for her and her betrayal, realising that she never loved him but only used him for her own sake. He makes some sort of machine/computer, transferring Cassandra from her human form into a digital form (maybe a cyborg with a computer brain? Maybe just her consciousness into a computer). But after she can't have proper human emotions and she doesn't remember fully what happened? And this transformation is her rebirth.
Also I am not really sure how Inertia Corp fits into this, maybe they help Sparkles* rebuild Cassandra? But why?