It's the Electric Grandmother!!!!
I loved this movie when I was little. The Electric Grandmother is delivered in a box and has some kind of electric glowing heart. The kids love her. At the end her batteries die or something and she has to go away. I cried and cried and cried.
OK - I just found the movie online...here...it was a TV movie.
Plot Summary for The Electric Grandmother, 1982, TV Movie
To a family whose children are traumatized by the death of their mother, help comes in a most bizarre way. They receive three pieces, that when joined together, give a recording for an offer for an electric grandmother. They go to a bizarre factory, where they customize their new grandmother, and within a short time, she arrives. The android is equipped with everything needed as a parent and the boys are charmed. The daughter, however, still misses her mother and she bears no welcome for this interloper...
http://us.imdb.com/title/tt0083876/