You have to open the sunroof about half way or more, then unsnap the 4 clips on the forward edge of the sliding roof panel that hold the liner to the panel. Once they are clear, you pull the headliner forward and up out the roof openning.
There is some kind of guide tube sleeve on the inside of the headliner that you have to engage when putting the unit back together. This is new to me, and I am looking at the CD manual instructions. I have personally only worked on the simple sliding roof without the pop-up feature, and it has no such provision.
Once you get in there you should be able to figure out the mechanism and close the roof by hand. You will not be able to get the liner back on under those conditions though as the headliner is wider than the opening in the interior and springing it into place will likely make it deformed for life.
Good luck, Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)