Pit Of Heresy Symbols At A Door

[RiskZone]

The code outside the only door that works to enter at the Pit Of Heresy has 24 symbols, there's a total of 24 doors. What does this mean?

Inside that door there's a stone with a symbol looking like an "A". Anyone knows the meaning of it too?

Screenshot of the door https://steamcommunity.com/sharedfiles/filedetails/?id=2821982648
Screenshot of the symbols https://steamcommunity.com/sharedfiles/filedetails/?id=2821984018
Screenshot of the symbol inside the door https://steamcommunity.com/sharedfiles/filedetails/?id=2821986122

[EckyThump]

The symbol in the final screenshot is part of Xenophage's quest, the 'Path Uncovered' step. https://www.youtube.com/watch?v=mGADvIIz43I
I'm assuming the other parts somehow guide you to it, but not sure how.
Each doorway has a symbol chained above it but I don't have good screenshots of all of them. It'd be interesting to know if the original set of guide writers just brute forced a solution by checking all the doors or if someone worked things out by finding a solution in the symbols.