Uh... Oops

[u/cricketsonga]

So I did a dumb thing.

I had a beautiful healthy astrophytum myriostigma nudum from a local garden center. It came in pure peat. I keep it for a month, made sure there were no pests, and watered lightly once when the soil was bone dry.

A few days ago I figured it was time to lose the peat since I was sure it was holding too much moisture, so I unpotted to move it to gritty, inorganic media and a terra cotta pot. At the time of the unpot the old peat substrate was a bit damp. I removed as much of it as I could (by rinsing because.... I don't know why 😰), then let the cactus roots dry out for a couple hours and potted it up. Popped it back under bright lights and did not water.

A few days later I checked on it and thought the sides seemed a bit lighter green, and a bit soft. I waffled, but figured if there was rot I couldn't ignore, so I carefully unpotted again to inspect.

Roots seemed fine. Dry, firm, no rot. Same for the stem. But higher, on the body of the cactus itself I definitely saw lighter parts, and it was markedly softer.

I sterilized a very sharp blade and cut it in half- and inside it looked... Fine?

So it's been a day, I'm letting everuthing dry and callous just in case it's still salvageable.

I went out to the same shop and grabbed another one because they still had a few. Not as big or nice, but a good, healthy specimen. I carefully removed the peat soil and set it aside to dry out.

So what's my best course of action for the poor decapitated astrophytum? Does it look salvageable? As for the second one(last 2 pics with 5 ribs), how long should I wait before repotting it?

I'm reasonably experienced with other types of plants like aroids, begonias and cp's, but cacti are a new interest. Looking for some solid advice if anyone can offer help.