Thank you for sharing your story. I had almost the exact same experience except I walked back to my hotel and was looking over my shoulder constantly in fear that I was being followed.
It was frightening to be trapped in the room and pressured to pay. I also considered fighting my way out but, same as you, didn’t know if they had weapons.
I told them to call the police if they thought I owe them the ridiculous sum of money they’d demanded. They said they’d call the mafia to handle me. It was awful.
It really soured my overall experience in China and makes me distrust everyone in this country now.