WARNING: This page is about a different car, the 2024 Audi S6 and 2024 Audi A6 Quattro. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Removing Inner Insulation
Courtesy of AUDI OF AMERICA, LLC
-- Push the antenna wire -2- in the mount -1- all the way into the tool head.