The battery is likely dead and needs to be replaced but the remote s may also need to be reprogrammed to work.
Vw t5 sliding door lock mechanism.
A quick video of how to remove the sliding door handle on a vw t5.
Here s a simple solution.
The swing arm of my sliding door lock fell off and i was unable to open the door with the key.
All that has happened is a very small spring has broken or fallen out.
If this happens the problem is with the remote.
Locks work from the switch but not the remote.
This issue also indicates a bad lock actuator.
My actuator seemed to be making a little effort when called to do so via fob.
A very common fault on the vw t4 door locking mechanism is dropping the door pull.