E25+ E25+ deck re-coring

When we bought our E25+, I was certain that there was some wet/rotten core on the starboard side area.
This forum was an amazing source of resources and good folks that help me figure out how to approach this repair, This is why I want to keep adding to this community by documenting how we tackled the rotten core in our boat's deck.

Thanks to @trickdhat that helped me a bunch. thanks again !

When you find a rotten core, there are different paths for you to approach this...