Ending up paralyzed after a failed suicide attempt is what I fear and is what sounds horrific to me. I think that maybe if someone wishes to succeed in ctb, maybe they should focus on doing everything to minimise the chance of that happening in their first attempt, like by making sure they have significant time undisturbed, and just researching the method.
I've read about people who attempted the hanging method and ended up with brain damage because they were found too early so that is certainly important making sure that doesn't happen. But I think that with ctb options for an actual brain damaged/paralyzed person it depends on the injury and the extent of the damage, but if someone is severely paralyzed I cannot imagine them finding a way to ctb unless they are able to be euthanized which sadly isn't legal in many countries. This world really is hell.