Diagnostic Aids
WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
If the power sunroof system fuse is open and a short to ground in the accessory voltage circuit is not detected, the fault could be a short to ground in one of the power sunroof control circuits. This would open the power sunroof system fuse when the sunroof switch is pressed.