Key help please

[Worker]

I have a gold gti and I cannot unlock my car with one key.
I changed the battery two weeks ago.  I used it to open the car door and it wouldn’t work.  I looked in the handbook under trouble shooting and followed the instructions to synchronise it.  But it still won’t work. 
Can anyone offer how to rectify this please?
Thank you.

[Watts]

Does it work at all ie does the red light come on when you press a button? If not, check that the replacement battery is okay. I seem to recall that people have had problems with some battery makes not working in VW keys which is why I have always used Panasonic batteries, no idea why. You could try swapping the batteries between the two keys to rule them out as a problem.

[Worker]

I have tried different new batteries.  They are Duracell.  The red light doesn’t come on.
The other key works and the battery comes from the same pack.  They were both replaced two weeks ago.
I have tried another replacement but still no joy.  Worried that I only have one key.

[Watts]

Sounds like a new key needed then. A quick google gives lots of options.

You have tried the battery from the working key? Your reply is not clear. Just because a battery is fresh from a pack doesn't 100% guarantee it's okay.

[Exonian]

The battery definitely isn’t in upside down is it?

[Adam T7]

The battery definitely isn’t in upside down is it?

Been there, done that🙄

[2007GTI]

If it really is dead, it happens, I’d call a mobile auto locksmith, plenty around, they will key you a spare key for £150-200 when I last checked.

[davo245]

On a 7.5 keyless start cr is it just  matter of changing battery in key same as other golf's?

Do you need to do any re programming of key afterwards?

My mate hs just swopped battery on his key 2018 gti with keyless and now he just gets flashing red light on key he says nothing else.

I told him just to swop battery as I have done on my current mk8 gti and my 2018 gti ( non keyless and both worked fine)

Any ideas or help appreciated??

I have told him to try a other new battery instead but just thought I would ask on here as it being a 7.5 with keyless the process should be any different?.

[SRGTD]

On a 7.5 keyless start cr is it just  matter of changing battery in key same as other golf's?

Do you need to do any re programming of key afterwards?

My mate hs just swopped battery on his key 2018 gti with keyless and now he just gets flashing red light on key he says nothing else.

I told him just to swop battery as I have done on my current mk8 gti and my 2018 gti ( non keyless and both worked fine)

Any ideas or help appreciated??

I have told him to try a other new battery instead but just thought I would ask on here as it being a 7.5 with keyless the process should be any different?.

No reprogramming needed on my 2020 Polo GTI+ with keyless when I changed the key fob battery. I assume the same would be the case with a mk7.5 Golf.

Lots of non-genuine batteries out there for sale on the internet. I tend to buy my batteries from the local Screwfix; the batteries they sell always seem have a very long shelf life with an expiry date many years into the future. If there was a problem with them, then buying them locally means I can easily take them back for an exchange or refund.

[sipj]

I have a gold gti and I cannot unlock my car with one key.
I changed the battery two weeks ago.  I used it to open the car door and it wouldn’t work.  I looked in the handbook under trouble shooting and followed the instructions to synchronise it.  But it still won’t work. 
Can anyone offer how to rectify this please?
Thank you.

Just to note with Duracell button batteries - they put a coating on these listed on the packaging as "repulsive taste" which stops kids putting them in their mouth.  I have found I need to clean of the battery before using it as the coating effects them working.  This was specifically in Apple AitTags, but if you have only tried Duracell, may just be worth cleaning it off first.