Hello
@NeilR25, it will require your utmost patience to steer away from watering and wait for the roots to form. The last time I had something similar happening, I think it took the whole Spring and Summer season to recover, cacti is just so slow growing, and got to use a very gritty mix as mentioned already. It was a learning curve for me too that time and taught me a hard lesson to always make sure media is well draining and containers being used always have drain holes.
Good luck on your plant! It does have good potential, so be very patient as you wait. Try to position them in a bright light/warm spot for now, like a morning sun area.
