Head back to the entrance of the fountains. The central area should be open now.
edit: Oh, WAIT, NO. I'M AN IDIOT (big surprise there). The padalo still takes you to the path of the puzzle once you've solved it
Edit 2: Yep. Another fix on the list.
By the way, word of advice: the recommended level to for the first boss fight is 6+
Just wanted to point that out there