Yeah, it wasn't his "cage" that scared him, it was something that he saw on the floor in that specific room. Again, they're extremely intelligent and it's exactly the same as we would react if we saw something that scared us on the floor in a specific room. We would be hesitant to go back into that room and sit on the floor. The fact that he's sleeping in his cage with no issue but won't go back on the floor in that specific room is indication of exactly this...Like we said above, it could have been literally anything, an insect or spider, or some other "critter" that he saw on the floor in that room, or it could have simply been a shadow on the floor. It could have been something that he saw on the carpeting due to the light in the room. Something on that floor in that room frightened him, and now he's scared to go back into that room and be on the floor...If his other cages are in that same room but are off of the floor and he's fine being in them, then obviously it's not that "room" itself, but rather specifically the "floor" in that room...
Hopefully as time goes by he'll either forget all about whatever it was that scared him, or he'll just slowly lose his fright over whatever it was that he saw...What you might try is to forget the cage for right now, leave it in your bedroom, and simply take him into that room and YOU sit down on the floor in the room with him, and see how he reacts. If he's still noticeably scared/agitated by being on the floor in that room, even with you sitting on the floor, then just try to calm him, talk to him gently while you're sitting on the floor, give him his favorite treat while sitting on the floor with him, and try to get him to again feel comfortable on the floor in that room. It might take you doing that every day with him for a while, but eventually he'll again feel comfortable being on the floor in that room (their favorite treats work wonders, as they associate them with only good thoughts)...And after he's totally fine with being on the floor in that room with you, THEN again try bringing the sleeping-cage in and putting it on the floor, as it's not that cage that is the issue, it's the floor itself. So once you can get him over being afraid of the floor in that room, then having the sleep-cage on that floor won't be an issue at all anymore..