They turn their nose up at robotic parts that aren't built for them until their arm starts to give out under them, unwilling they take these pieces, eventually as they add each part, they come to find they're happier, lighter, freer then they ever were before, they start enjoying the colours and shapes of their new body, the darkness they were in slowly transitions into light
Eventually, just as they were about to escape from the heap, they pot their old gun, the gun they had used to hurt innocents mindlessly. Next to it, a different arm. They consider both, their final choice. after a moment they detach their old arm and replace with with this new one, leaving their gun behind forever as they ascend into the light