

X1 Carbons of several generations have been notorious for their Thunderbolt defects, which appear after a while. For instance this or this (sorry for the Reddit links), and there are others related to connecting to screens. Right these days I’m dealing with the Thunderbolt-charging defect in my Gen 9. Luckily still under warranty.
Best of luck with your problem! I suggest you use your warranty if still active (and better with on-site assistance than sending the thing).
Can you try the icanhazpdf hashtag on Mastodon? https://c.im/tags/icanhazpdf