Key Battery, Removing And Installing: Removing

-- Fold out the key blade.

-- Pry off the cap -1- on the back of the key -2- in direction of the -arrow- with a screwdriver.

Fig 1: Prying Cap

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.

-- Remove the battery -1- from the key -2- in the direction of the -arrow- with a screwdriver.

Fig 2: Removing Battery From Key

Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.