To make it short: Naija hasn't endless options what she can do. So it shouldn't be so hard to figure out how to remove the helmet. Try one of her oh so many songs. Maybe the one you used when removing the helmet the first time.
Yeah I tried using bind whenever he swims by me at the cave and it doesn't work....I also tried the Li's song and he doesn't respond and come over
You have to corner him <.<
She will CLEARLY say when it is time to remove his helmet. And he won't move AT ALL during that time.