My 360 camera in my 2014 Rogue stopped working only on the drivers side, which is greyed out. I put in a new head unit about two weeks ago and it worked fine until yesterday. I pulled out the head unit and checked all the wiring, which seems to be fine. I don't know if I should take it to Nissan or pull it apart again to see if there is a loose wire somewhere. Please help!

The head unit doesn't process the bird's eye view, there's a separate AVM Controller which does that. It's located behind the glove box. The AVM assembles the composite pic and then forwards it to the head unit as a complete image. One grayed-out panel usually means a bad cam, in this case the one in your left side mirror. You can find all the info here for both Navi and non-Navi AVM's, including wiring diagrams:
https://www.nicoclub.com/service-manual ... 4%2FAV.pdf

Im not sure how to look at this diagram its confusing as hell lol. Any tips on how to go about it, I appreciate it!

The AVM is on the CANbus if you want to get it read with a high-end scanner. But first, is there a red "X" or other warning icon in the grayed-out area? If there is, then it's possibly a wiring or controller issue. If it's just gray, that's a bad cam. Gray without an icon means the cam is online and communicating but there's no picture, which means the cam's CCD is dead.