What is this about?
Seal Holy circle
I like the combination of the first two. "You tried to augment yourself with machine parts bridging the gap between living and unliving matter through necromancy," but there's something about holiness, something of Heaven or something celestial, that works against you.
So there are two questions we've got to ask here:
How does necromancy cross with machines? And what does the Celestial Power have to do with machines?
While I'm afraid that we might fall into some unfortunate implications, let's say that there's an industrial element to Hell. Necromancy and the Infernal Power go together like a charm, I guess, and it's because this is some devilish kind of machinery that holy magic works against it. Why don't we do a bit of a biopunk/cyberpunk dichotomy here, and make Heaven a genetic engineering/flesh-shaping kind of place? Like the elements of H. R. Giger's artwork got a divorce and half of them went off to Heaven and the other half to Hell, and then they both got contracts to redesign the places.
And our humble character made a deal with Hell to rework zir body into some half-machine thing that would never die.
Its phylactery is a small object. Let's make it a battery. The character will keep on going so long as it has power, so you have to destroy its (basically unlimited) power source. Maybe, to go beyond the bounds of the CYOA but also make things more interesting, the battery is charged by dying. It can conceivably run out, but if somebody dies in its vicinity then the character will start running again.
And some silly merchant holds the battery. For now.