...Flip and go to the place where you previously put hearts, hopefully, this is the one with the ground pound pixl... But eventually you see a couple of stumps, flip and look to the right... There's some posts that resemble those stumps, hammer them just like the order you see them... I think you have to push up one that's flat, you just jump on it and it'll come up...
The next part is straight forward.
Man, that was hard to explain and I don't even know if it was the right one.