Although manualising (!) the doors is not something we recommend, it is useful to know it can be done successfully as they get towards the end of their lives.
The other electrics still work and the door pulls in and locks OK.
If the cable is broken or the main motor has failed, then the cable ends can be popped off the lower hinge.
Once the cable has been removed and tidied away, the door can be used manually and is much easier to slide without the friction moving dead mechanicals.