I had an issue with not being able to get Deacon to exit his Power Armor. No matter what I did he just kept going on about his Recall Code and asking me if I read it or not. I had forgot that he had given me the Recall Code earlier in the game, which I did read it then but I did not read it to him. So once Deacon entered his Power Armor and I tried to get him to exit the Power Armor he just kept going on about this Recall Code.
I didn't have the Recall Code on me, it was in a storage bin at Sanctuary, so the dialogue to read the Recall Code never appeared. Once I had the Recall Code paper in my possession I was able to talk to Deacon, and have the Read Recall Code dialogue as an available option. Once I read it to him, Deacon talks with me about not trusting anyone in the Commonwealth and when he finishes you can now Talk with him again and ask him to Exit the Power Armor.
I have seen a few people ask about this on Twitter and Reddit, and if you do a Google search you will see quite a few people who have had a similar issue. I just figured I would do this short video for anyone who might have had a similar issue!