The firmware on the VSSL is updated automatically. These updates happen on reboot or every 4 hours if no music is playing. The firmware is only updated if a newer version exists.
When the unit is downloading the firmware, the zone LEDs will indicate:
When the unit is in updating mode, the
Since each zone is independent, each zone will need to have the firmware updated. The lights will indicate this for each zone.
After all zones are updated completely, the unit will reboot.