I have a dioon spinulosum caudex that I have been trying to re root for a couple of years. It had rot at the bottom. I dipped it fungicide and also dusted it with a growth hormone. I haven't seen any change or life since. So I don't know if it's dead and how long should I keep trying to root it. It is firm. I just checked it, no rot, but no roots. I don't have it in sand, the nursery gentlmen recommended a cactus mix.
I keep it outside in the summer and now I have it inside.