This was an interesting idea both in the sci-fi element and the decision to make it a first person confessional piece.
Ultimately, I think the confession borders on the incoherent because the woman shits from memories to dreams with nothing to tether the reader to the reality of the world. I mean, where is she when she's thinking and doing these things? How is she leaving this message (?) to her daughter. Is this a letter? A video record?
I think it would be improved by brining the elevator journey to the surface to the forefront and framing her recollections by having her thoughts prompted by the things she sees on her way down. Perhaps have her recording the message as she does so.