I am sorry to hear that. Here is a streamer who played and gets to the boss around 7min in the clip. You can watch that to see the ending or location of the boss. Not sure if you left any messages open that could cause a bug not to trigger the void?
Came to report the same bug. I just get the music and then I can't do anything anymore. I'll just restart the game though, because it's quite short and I did enjoy it :)