People like Fire Departments and Building and Safety Departments are a bit sticky about what you put on a door to open it that might, incidentally, keep it from opening in case of a fire and resultant loss of power.
You said you wanted something to close a door, so a magnetic door-holder-opener along with a spring or hydraulic closer sounded about right. Then you said you wanted to open the door with it. That's a lot harder to make safe.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
