Whenever I put her in reverse, the lines show up but the camera is just a black screen. I ran the system self-diagnostic and it says everything is connected fine and the camera is an OEM replacement because the first one stopped working too. My mechanic said it needs to be “paired” but I’ve looked online and haven’t found anything

 

Oem oem or aftermarket ?
When I was installing mine it would go blackscreen in reverse before I bypassed the e-brake.

 

Moving this thread to the appropriate sub forum, Audio/Video section.

 

Like stock replacement

 

If you want to keep the stock configuration, maybe someone else can help.
You could always use OEM equipment in an aftermarket configuration.
It works.