Oh wow - I found the exact same "door" last week - 62K coming back from JFK...I actually thought I'd broken the panel as there was a click when my bag fell against it but then I could see it was supposed to open...I was actually quite careful after that as I didn't want to press a button and have the wings drop off....

(and like yours, the plane was filthy - the ingrained dirt all around the seat was truly yuk )