WillC said:The outer (cambium) layer on the lower portion of the stem is the critical pathway from the roots to the upper portion of the plant. Once that is dead or damaged, and your is, then the roots are no longer able to support the rest of the plant.
You could try cutting off the stem above the stem damage and try propagating that upper portion. However, larger, older stem sections have a much more difficult time propagating new roots than smaller stem and leaf cuttings.
When propagating, use a very small terra cotta pot filled with a damp porous potting mix.