Here is the process to exchange the battery on HA700 control unit or detectors:

Step 1:

Check the status of LEDs status, if one of them is flashing you need to do this:
        personal code + 1
        personal code + 4

Step 2:

Enter to the test mode:

        personal code + 03

Step 3:

Now , you can change your batteries without the siren ringing

Step 4:

When you finish, push on ( * ) to exit the test mode