Hey all! I have made some changes to make the boss fight more intuitive:
-removed getting damaged when too close when boss is vulnerable
then added extra audio and visual queues to the boss.
Turn up the volume if you cannot hear anything. I promise the audio is there. I just set mine to reasonable levels so it doesnt hurt your ears at 80% volume like a bunch of the other games tend to do.
If you have time to redownload it and try again, let me know how it goes :)