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Here's what you have to do:
- Fully vent the sunroof with the forward side of the button (tilt the back of the sunroof up all the way)
- Press the same button (the forward part that closes/vents the sunroof) again and hold it for about 30 seconds - the owners manual says to hold it until you see the sunroof move, but mine never did so maybe don't worry so much about that
- Then release and immediately re-push the same button holding it again - this time it should start moving. It should close, then slide backwards all the way, then slide forward all the way and end up closed again. Don't release the button until it is fully closed (if you accidentally do, then just start this process over again at step 1)
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Your sunroof should now be fully functioning again. If you press the backward button now, it should open exactly like it is supposed to. If there is some sort of larger malfunction in the unit, it will enter safety mode on step 3 and will move in about 2 second intervals - if this happens you just need to keep pushing the button over and over until it closes and then you need to probably bring it in to have it diagnosed.
Good luck and happy driving!