will give it a go, when hubby back from dog walk!
This post is quite comprehensive as to the causes of the stuck side door, how to release (as I suggested as the first option) and then a deeper dive into how to open the door if the push and pull method doesn’t work.
Thread 'Sliding door stuck'
https://vwcaliforniaclub.com/threads/sliding-door-stuck.39728/
The key issue is that if the push pull doesn’t work, the door still needs to be opened to get the door card off.
See the power off method at post #15
This is how the lock operates.
There are cables from both internal & external handles to the central locking motor and then a drive rod to the rear lock.
The electric side also drives the soft close feature. However, in the event of complete electrical failure the mechanical cables (especially the inner handle) operate the drive rod and unlock the door (as required if the vehicle had lost power following an accident)
The “lock” is performed by a strong metal hook or pawl being rotated and engaged around a hoop on the vehicle “C” pillar
1 Hook open and ready to latch

2 Hook encircling rod and starting to lock
(Screwdriver simulating hoop on “C” pillar)
3 Hoop on “C” Pillar that lock hook-engages with as door is pulled into closed position.
NB first part of the hoop latches the door and the soft close electric motor Rotates the hook further and engages the hook with the second part of the hoop, clamping the door tight into the opening.
If the electrical contacts on the front of the door have been obscured by debris and not making contact then the soft close is likely not operating when trying to open the door so not releasing the pressure on the door lock preventing you having enough leverage on the handle to use the mechanical mechanism to release the lock.
4 Internal of rear of door showing soft close motor (circled in red) and drive rod/cable (circled in white)
Good luck