If you go too far on that route before you try to burn the wood, when you come back, every single cave will freeze. That's why I was stuck!
There was only an optional boss to fight in the ice temple. In any case, the fight system is kind of broken since I didn't spent too much time on it. This game was a birthday present for a dear friend, and I only released it because to have it somewhere, I'm glad people can enjoy it a bit even then. :)