Chernobylite

Board Investigations are easy, and you basically walk through the level and listen to dialogue, so here is a guide of how to unlock them:

Board Investigations are found in your bedroom at the base on the big chalk board directly across from your bed, and they super straight forward. In order to unlock the Board Investigations, you have to find a certain amount of clues and secrets in the main quest line (up stairs where you pick up the binoculars to select missions) which are represented by question marks in game on your HUD compass. If you don't have enough secrets and clues found, you won't be able to do a Board Investigation, so my suggestion is to find as many of these clues/secrets as you play the main missions, or you will have to come back later to do supply drop quests to find these. I made this mistake and just did the main quest objective and peaced out, so I had to come back and mop up later by doing supply drop quests. This should help cut your play time in half.

Other than that, Board Investigations will be sections dialogue that tell you the story and unveil what happened to your lady and so on. You just go to each green glowing figure(s) and listen and wait for the dialogue to wrap up until you can move on to the next section of the map for the next piece of dialogue.

Good luck!