SOLVED: Why is my USB port not working? - Dell XPS 15-L502X - iFixit
Found a Dell XPS L502X at the dump! It took 13+ hours of repairs, Windows installations, and driver installs, but it was all free! I literally repaired it with a glue gun.
User manual Dell XPS M140 MXC051 (English - 180 pages)
Dell XPS L502 USB Daughter Card
DELL XPS 15 L502X - UNKNOWN BLUETOOTH DEVICE Issue - Dell Community