I had a freak accident about 2 years ago with one of my amazon tree boas. I was in the room, feeding some boas. I always glance around and check out the others while doing this since it's when they come up to the front to see if they are getting fed. Looked into this ATB's cage and saw the snake coiled up half in the air in an odd position... 'what the...??' get closer (she's on the top shelf) to see what is going on and her rock hide is sitting ON her neck. She is not breathing. Her neck area is swollen. Luckily it must have just happened because I took her out, did some 'CPR' and she was still alive. It was traumatic for both of us (it took a while for all her movement to come back and a few days before she was acting normal again). The ONLY thing I can think of - these cages have perches. She was in her hide, went up onto the perch to see what I was doing in the room, had her tail hooked on the entrance of her cage, lifting it up, then as she was going back to the floor of the cage, her tail let go and it fell onto her neck.
If I hadn't looked in the cage, she would have died.
I have since removed all rock/heavy hides from any cage that has perches.
Perhaps it was something similar in this case? The user said 'dislodged' maybe it was up high or suspended? User also mentioned flip, maybe it somehow flipped it over onto itself? very strange but odd things DO happen from time to time.