module lost it's calibration
The sunroof motor's hall effect sensors got thrown out of whack or the memory was cleared and the module lost it's calibration, or "initial position setting".
One solution is to re-calibrate it.
Workshop manual steps:
1. Press the CLOSE switch to fully close the glass panel.
2. When the glass panel reaches the fully closed position, temporarily release the CLOSE switch and press it again for approx. 13 s continuously. Continue pressing the switch until the glass panel automatically stops at the fully closed position after reaching the mechanical lock position.
3. When the glass panel stops at the fully closed position, temporarily release the CLOSE switch, then press it again within 5 s and hold.
• Press the CLOSE switch continuously until the glass panel opens to the fully open position, returns to the fully closed position and then stops.
4. Release the CLOSE switch when the glass panel stops at the fully closed position.
bad/worn sunroof motor
If you tried calibrating it (more than once) but it still won't open, then you should inspect your sunroof motor and replace it with a new one.