Lenovo ThinkPad Universal Thunderbolt 4 Dock User Manual page 8

When the dock is connected to both your computer and ac power, this indicator shows the computer status:
LED status
Solid white
Blinking white slowly (1 second on/off)
Off
When the dock is updating firmware, this indicator shows the update status:
LED status
Blinking white rapidly (0.5 second on/off)
Off
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Universal Thunderbolt 4 Dock User Guide
Computer status
On
In sleep mode
Off or in hibernation mode
Firmware update status
Updating
Completed