I think you might just be doing it wrong. Try this:
1. Turn off your calculator, wait a couple seconds
2. Hold the restart button
3. While still holding the restart button, press F2, 4 then AC/On (MAKE SURE YOU DO IT IN THE SPECIFIC ORDER)
4. Let go of the restart button while still holding the other buttons
5. Let go of the buttons in this order, F2, 4, AC/On (The screen should be blank)
6. Press AC/On, then 9, then x
If this doesn't work then I don't know. Also important note, make sure you wait a couple seconds in between each step