How would a crew of a spacecraft get home if 'everyone' on the spacecraft becomes incapacitated, immobilized or go unconscious?
The crew is alive and stable but unable to operate equipment.
Is there automation in the system that can be invoked in a contingency? Can operators from the ground remote control the space craft back to earth? What about the reentry stage?
They could have suffered from some form of paralysis, or experienced an event that knocks them out or something else happened via poison, bacteria or virus.