Locked Door still not open after Death cinematic ?

[myndovamadda]

I finished the Richter fight, then watched the end credits. Online guides and other players say to go back to the locked door in Northwest part of map and it's open. Mine is not. I have run several characters to the door to see if only one of them is allowed inside. No such luck. I've tried to find the "Pile of Secrets" and "Wood Carving Score". I can't find them.
Please help, I'm missing something and my progress is stopped until I find out why.

[Desolate Pond]

It's southwest, not northwest, underneath the forest is another entrance to more castle area that unlocks more things

[myndovamadda]

Thank you very much. I found it !