Pierre, there can be a few things.
The easiest is a corroded starter cable - you may bring the guy's car to life in seconds and make his day
https://www.youtube.com/watch?v=mhNawwOORiM
There can also be a battery issue if the battery was drained right before the issue
Antenna ring is also a possibility
All above would have an immobilizer message
Then maybe the steering lock is damaged if he can't insert or turn the key
If the car just doesn't start, the awd DEM can be at fault