In what could be another potential PR headache for Dell, the latest 1.0.7 BIOS update for the XPS 13 may be accidentally rolling back systems. It's recommended that XPS 13 owners do not install this latest update until Dell either reuploads a new BIOS update or directly addresses users' complaints.
https://www.notebookcheck.net/Latest-XPS-13-9360-1-0-7-BIOS-update-purportedly-bricking-systems.243702.0.html