Hi,
Here’s a link to the [https://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_xps_laptop/xps-15z_service%20manual_en-us.pdf|service manual] for the laptop.
Scroll to p.81 to view the necessary pre-requisite steps and then the procedure to remove the display assembly. This will enable you to remove / replace the LVDS cable.
Replacement cables are available online. Just search for ''Dell XPS 15Z LVDS cable'' to get results for suppliers of the part.