I think she was too smart to have turned her phone off, I don’t think it happened to die. It was forced off. Immediately. I think she knew having clicked her seatbelt stuff was going south.
Also, I think it’s probable he did not act alone. Why? Because I feel it was too much for him to do. If she was under threat in the car, the moving her to the house would be 10x harder than if she was still comfortable with him. Managing her in the car from the get go would be difficult. Incapacitate, take phone, drive, keep her from escaping, move her to the house, etc etc. coupled with the fact he had various people at the house and seemed well networked online, he could have gotten accomplices together. Like Holly Bobo.
A weapon would make things easy, but not really. With just him, she could have run when they got to his place. She could have run at a stop light. He was driving!
With a second guy, all of this would be very possible. Not saying there is a long history of single perps doing a lot. He was driving. You can’t really even keep a handgun on someone and drive, I don’t think.
If she voluntarily turned her phone off, the she travelled willingly with him.