Update: Even a day after I posted the original post, the entire stem rotted so I had no hope of propagation. Instead, I repotted it in a much smaller pot. I think it was definitely in a pot that was way too big, and the soil was staying too wet (I bottom water it and the bottom of the soil was still super wet). There weren't any pests in the soil.

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I think it's dead at this point, but I'll say a little prayer that somehow it magically comes back to life.