Hi,
I know this reply had a way too much time gap, but i wish this can help other people in the future. and if you havent fixed yours as of today hope this post will you!.
I had done a lot of reading, post from everyone from all over the internet. i came across with your post and turns out we have the same problem, the roof latch thing is like "stuck" inside right? well supposed to be it needs to be all the way out so i can hold down the bar thing that latches with it.
as i researched about this part. (part no: 54347043870) for the roof latch and its number 23 on the diagram.
if you study the picture of the roof you will understand that this part is like 2 connected part. The locking part and the wiring part that kinda pulls it when using it automatically (well i am manually putting my roof close/open).
So what i did, i tried to remove that part it has like 4 bolts (2 each sides) and if you can try not to break down any kind of plastic that would be perfect. since mine is a little old, everything just kept pulling apart. Once i removed that part i studied the locking mechanism, and guess what i dont really need that wire pulling back the lock so i cut it (which i done recommend if your roof still fully working) since mine is manual close/open roof now. Then it pushed forward, and now you can see it can just lock itself now.
well this method works for me, i need to break things to fix it. but its worth it i guess, i havent top down my car for the past 3yrs..
hope this post will help you.