There is a small hole in the side of the key head. Insert a paperclip into the hole, and pry the back off.
Replace the battery in the remote
There is no battery inside the key to replace. The key actually charges through your ignition. If its not functioning you will just have to order a programmed key from the dealership.
go to a auto parts store like autozone kragens they should have it if not go to the dealership they can get it for sure
change the battery in the remote you can test your remote at auto zone for free
cr2032
CR2032 3 VOLTS Energizer
Open it up and look see. You now know what replacement battery to buy.
you have to pop off the back of the remote. i had to get someone at a dealership to do it. you know nothing is simple on a vw...
Walmart or any place that sells small batteries for watches or calculators.
Each remote takes ( 1 ) coin style battery ( CR 2032 ) or equivalent according to the owners manual
Usually you change batteries when it dies out on you. But there are also indications that batteries need changing. Like it's not working smoothly, or remote signal seems weak, or the flashing battery indicator. Best if you have a spare set of batteries on hand.
If you don't know how to change something as simple as a battery then perhaps you shouldn't try. Buy a new a battery at Autozone/Advance and they will install it for free in less then 5min.