Magnetic door holders are typically held by power provided by the FACP, when the power drops they release. Whenever the fire alarm activates, or when the fire alarm loses power, it should drop power to these door holders and the door should close. You shouldn’t need a manual release, and if someone wants to shut the door for whatever reason in a non-fire alarm situation, they just have to give it a good yank, it’s only 30-40lbs of holding force usually.
Chris+s is correct about the door holder operation. The 972S is made for heavier doors and is rated at 75 pounds holding force. Might need a really good yank.
If an electrical manual release is still desired, it is quite easy. Since the holder releases the door on power loss, all that is needed is a normally closed momentary switch in series with the holder. Push the button, holder looses power, and the door closes.
I’m just curious, if the doors were never set up to operate in this way (automatically closing on an alarm activation), why set them up now?
Also, the setups I’ve see utilize a listed fusible link that would melt at 165° and release the door. Never heard of a setup that would require a rope to burn to release unless it’s something before my time! I wonder if someone has removed the link in your case?