Replacing smoke detector alarm battery help

I know I've done this before but for some reason I am stuck. I have a smoke alarm where the battery compartment is being blocked by the permanent power. I cant disconnect or a monitoring alarm will trip (i think?). There is a great deal of tension here and any more force I feel will break the connector. So how do I open the battery area here?

 

Turns out I did have to disconnect. However, I replaced the battery and my wall mic is still beeping. hmm

 

At this time I'm going to try removing the two alarms from power, removing the battery and holding the test button for 15 seconds and killing the circuit breakers for the rooms

 

I killed every circuit breaker in my apt and the wall mic is still beeping

 

In the detectors yes, but at the moment they are offline. I can't seem to be able to reset this mic.

 

The mic appears to be powered outside my unit and there is no reset switch

 

another what?

 

nah, i'm in a small 1 bed apt and have been for 8 years :)

 

There was one breaker I didn't kill and that was for the washer and heater because there was a danger sticker and it needed some key to turn off.