Can you take a screenshot of that door that keeps closing on you? Not sure which one you're talking about in this case, just wanted to make sure I'm giving you the right advice (you can press F12 while in-game to automatically take a screenshot!)
No problem:
Now, as I said earlier, this room is marked as [?????] not only on the sign, but also on the map.
I got to it from p1m3, and since this is the only place that seems out of reach, I assume that blue item up there (behind the minimap) is the fragment? If not, and its just a power-up, then I'm at a loss.
I assumed its a fragment because you told me that its on p1m3, but there was actually no fragment on p1m3 (that I can see).
So, I can open that door by hitting the gravity switch on the top right. But when I do this, I drop down and there is no way up!
In order to get to that room, I have to reverse gravity first, otherwise its inaccessible. I did this by going from p1m3 to p1m4, and hitting the switch there to reverse gravity, then back to p1m3 and then to [?????].
I tried dashing in through the door (by hitting C) as soon as I enter the room, but it closes so damn fast its impossible to sneak through like that.
I honestly am at a loss as to how to get through with gravity reversed. And if I get through with normal gravity, there is no switch in there and no way up.
So.....I'm lost.