Log into your AccessCT. In the server configuration page, check Update

Automatically next to firmware updates, and press the submit button.

From the main menu, select Connected Devices under AccessCT.

Check your AccessCT, and click Advanced (at the top of the group).

Check Update Firmware and hit Apply Changes.

The AccessCT's firmware will be updated the next time if connects. When update is in progress, all three lights on the AccessCT will blink. Do not power off the AccessCT during this time.