WJH85 said:I may try to cut the top part and give it a last chance even though I know it is unlikely.
If you do this, use a sharp blade and cut straight across the stem. Inspect the cut surface carefully to be sure that rot has not reached that high in the plant. Leave the cutting in bright shade, somewhere with good air flow, so that it can heal. Wait a couple of weeks and then pot up the cutting so that it sits on top of the soil, not buried in it (about half an inch of buried stem is okay). Do not water right away. Wait a week or so to water. Then water sparingly, only when the soil has dried out at depth. There is a risk of the plant rotting out through the injured surface over the winter, so you need to exercise discipline with the watering can until spring, which is probably when the cutting will start to grow again if it has rooted.
The rescue will likely be unsuccessful unless you can provide different conditions from the ones the current plant is in. Lots of light is key, like a position right in front of your sunniest unobstructed south-facing window (assuming you are in the northern hemisphere). Use soil with good drainage (like regular potting soil mixed with an equal volume of pumice, perlite, or equivalent). Be sure the pot has holes at the bottom, is wider than deep, and does not exceed twice the width of the stem you are trying to root.
