You may find this part of the manual helpful:
Connection, Automatic firmware matching and LED behaviour
When powered, the ‘Power’ LED on the front of the AB168 will illuminate.
On connection to a mixer, the AB168 will automatically check and match its firmware to the mixer model and mixer firmware version. If an update to firmware is required, it will happen automatically. This may take up to 2 minutes to complete and if the AB168 is cascaded (connected through another unit), checking and updating may take slightly longer. During an update, the port ‘Lnk/Err’ LED will flash red and once the update is complete, the AB168 will automatically reboot.
When running the correct firmware and connected to a mixer, the ‘Lnk/Err’ LED next to the dSnake port will flash yellow to show link activity and the ‘Ready’ LED on the front panel will illuminate.