What should I replace? Not sure if it's an LCD issue.

I see Dan. I will totally consider doing some more tests and then replacing the display assembly which sounds a lot easier to do. Thanks for the links :)

Cesare,

Unlike the older displays which use a thicker glass. The retina series use very thin glass so instead of cracking or shattering which would clearly indicate a broken screen. The glass has a bit of flex so the micro traces along the edge can often get damaged (often called a TAB error). I suspect thats what happened here a bang along the edge or something heavy fell on the lid.

Wow, that's a great analysis, thanks! I suspect this is what happened since it didn't fall from my desk or anything like that. Do you think I may be able to fix the micro traces along the edge by opening up the computer and inspecting the internal components a little bit? The screen doesn't indeed look broken (I've typed LCD broken on Google and the images that popped up are a lot different than my current issue).

Sorry nothing fixable here ;-{ New display time.

Here's a vid that shows a bit more: Vertical lines in laptop screen - Free Quick fix. As you can see Karrissa applies pressure to reconnect the broken traces on the glass. This is not really a proper repair as the wedge solution only squeezes the connection together, the trace is still damaged.

Unlike the Asus laptop you can't get to the LCD on the MacBook to try the same and besides it's not a long term fix. The difference in hers (colored) Vs yours is related to the trace set, signal Vs power in yours it's the power side (Black & White)

Thanks so much for the video link and for your analysis on this, Dan! = :) I think I will either replace the display assembly or buy a new Mac completely. I will now try to apply some pressure to the screen as seen in the video and see if it works. The trace set signal vs power is so fascinating by the way, never thought you could tell which problem it was just by looking at the vertical bar/screen colors. Thank you!