I was never able to make it work, because that kind of body horror has never played to my strengths as a writer, but in the era when Pocket Books was publishing the Strange New Worlds anthologies I took a couple of whacks at a story about a character who gets injected with Borg nanoprobes and, while the assimilation of the body works and the Borg are able to hijack the nervous system, the assimilation of the brain fails, resulting in a character who is fully aware of what's happened to their body and completely unable to do anything about it. It would be a lot like sleep paralysis -- which I've experienced a handful of times in my life and it was absolutely terrifying -- but far, far worse, because at least with sleep paralysis a person will escape from it, while Borg assimilation is something that will never be escaped from.