A.R.
Put the potty chair in his room. Obviously this is his safe place to go when he needs to pee or poop. Honor that safety and put the potty chair in his room.
Also, don't flush the poop/pee down the toilet in front of him. Toddlers are attached to their pee/poop and can get upset when they see it threatened by flushing.
Read to him: Once Upon a Potty, and Everybody Poops ~ children's books you can find in your library.