my guess is the entire display. Unless you have like 5 specific machines that will put all your cheap separate display parts together properly, I'd just look into the easiest display replacement method possible, usually a $40-60 part, a whole display, lcd+digitizer/glass, sometimes they'll come with a mid-frame or whatever it directly connects to. Find videos on the DIY job, at least three to get familiar with every little step, trust me, I've wasted a lot of money on breaking new displays/glass trying to rush this stuff, make sure you know how to adhere the display to whatever it connects to like a mid-frame and/or bezel, what adhesive, glue and/or double sided tape, AGAIN know the steps to the very end before you attempt. Don't work on carpet. Maybe get one of those anti-static wrist bands.
I broke my last display screwing up the last step, stuck it down a hair off screwing it up then had to take it back off and broke it. Go slow. Good luck