Replaced this and the front-facing camera. Apple had told me that given both front and back were out, that it was a board problem. Incorrect. I successfully replaced the front facing and rear facing camera, and then the flashlight started working again too. Great stuff.
Totally stuck the landing! Thanks for the great guide. One thing. Possible to use more colors in color coding screws? Before I started, I had read through the guide, but presumed I only had 3 different types of screws, when in reality, red and orange change throughout in terms of the length of the screws.