I have no idea what happened; 1/3 of my screen blacked out
I own a 13 inch MacBook Pro with Retina display. I headed out about Sunday morning and to my horror, when I returned home, I saw that 1/3 of my Macbook's screen had turned like this. My heart sank immediately because I myself, had not dropped it, applied pressure to it or even, bumped it against any surfaces.
I honestly, have no clue as to what caused this damage, do you guys have any idea as to what the underlying cause may be? Also, on a side note, I had the entire display replaced about 1.5 months back due to stain damages, it was wavered by Apple.
MacBook Pro (Retina, 13-inch, Mid 2014)