I have a vibration rattle on the passenger corner of the dash. it is NOT the plastic piece under the hood on the outside of the car. It is under the soft mesh cover at the base of the windshield. I removed that mesh cover and found the rattle. Unfortunately I don't know how to remediate it without taking apart more of the dash.
For those of you who have ruled out the plastic piece on the hood, just bang your fist (doesn't need to be too hard) on the dashboard near the rattle. You should be able to cause a bit of the vibration rattle with your fist.
To remove the mesh cover, you need to remove a small plastic panel next to the glovebox. That will allow you to remove the A-pillar cover. That will then give you pry access to the mesh. Just be careful - the dash material scratches easily.
Video for removal instructions:
start at 3:52 if that link doesn't preserve the start point.
Once the mesh cover is removed, press down on the plastic near the speaker. While doing that, bang your fist on the dash again. If your issue is the same as mine, you won't hear the vibration rattle. So.... to fix, you'll need to shim under the piece you're pushing down on. I have no clue how to get under there.
But at least SC or mobile service won't need to spend time with diagnosis....