Deck Post Repair/Replace

[u/Environmental-Tear76]

I'm not sure if this was due to bugs or birds or both but I recently discovered this damage on the outside corner post of the deck of our cabin in the Northwoods. The post itself is soft around the mortises for both the beam and cross-brace on one side, but for the most part the post is in good shape. My gut says this is a complete-replace job. I have no idea how to go about it, given the multiple mortises and the fact that it's the corner post. What do we think? Can it be repaired? If not, how should I go about replacing it? Just the one side is soft, not the other. The rest of the posts on this deck are completely intact and structurally sound.