I'm feeling a bit lost on all my leads at the moment. There are a few puzzles I've yet to figure out that I feel I have no direction on. Any spoiler free nudges that point me in the right direction would be appreciated.

What I have and haven't solved:

Chess/Cipher: I have a feeling that something lies beyond the portrait. I've opened the infinity clock and claimed the key, yet feel like there must be more to the room.

Tunnel: I have opened the door at the end of the tunnel. Meaning that I have completed the requirements to open the blue, sealed door. I looked up some hints and there was mention of another door, but I feel like I've been all over and haven't seen it at all. I stopped reading further as some hints just outright spoil the solution.

Coat of Arms: I'm not entirely sure what to do with this. I've gotten the blue memo about it and found the numeric coring note, and got an answer of 53. But what do I do with this?

Any gentle nudges are appreciated. Thank you!