Changing smoke alarm battery

Trying to change battery in Visonic MCT-427 SMA smoke alarm. Following online directions, I called the 800 number before putting it in test mode. That routed me to ai chat. Finally got to an agent who was unable to understand the directions.

i have the battery. I put it in test mode. When I start to twist the smoke alarm counter clockwise to remove the cover, it alarms. I twisted it back on instead of proceeding. 

can anyone confirm that it should alarm that way and will stop as I disconnect it??

(direction I am using: https://www.xfinity.com/support/articles/installing-battery-mct-427-sma-smoke-detector)