I did this fix. I ordered a replacement camera module from etradesupply.com, which sells the preferred Omnivision version of the camera. Replacing the camera module itself wasn't too bad, but of course getting there was tricky.
After reviewing several YouTube videos on how to tear down an M7, here is the best one I found. https://www.youtube.com/watch?v=KPkwWxX8PU8
A few things to note:
1. Use a heat gun (or hair dryer) like he does. This makes the process MUCH easier. Some may say there is no glue, only clips, holding the phone together, but as you can see from my first attached pic, there is glue, or sealant, or something that seals the phone's back casing to the screen. It comes apart much easier when you heat it first.
2. Use a correct pry tool. In the video, you can see the tech using a rather long orange pry tool. I was able to borrow one of those orange pry tools from my local Sprint store, and it works much better than the common blue pry tool compared in my second attached pic. The extra bend in the tip of the blue tool is not necessary. You can see that the orange tool is straight with just a flat-head tip. Simpler is better in this case, and the extra length of the orange tool is handy for leverage. I used my blue pry tool to finish separating the edges and around the corners, but I left the orange tool in place during in the process, just as he does in the video. In my pic of the case after separation, you can hopefully see that there is no damage to the case after using the method in the video. I would NOT recommend using a metal pry tool if you want to protect the plastic edges.
3. Be VERY careful with the volume strip. There is a flex band/strip that connects the volume rocker strip to the daughter board, and it is VERY fragile! When inserting the pry tool above the volume strip (after heating of course), make sure to get above the flex band/strip/cable (as he casually mentions), and don't put any undo pressure on it. If you shove an incorrect pry tool into that space, you could easily break the connector band (see attached pic). I made that mistake on my 'practice phone' doing this procedure, which is my old bricked phone as a result of water damage some time ago. I used the blue pry tool on my practice phone (plus I didn't heat the phone first), and I broke the flex band cable in the process. Then when working on my daily driver phone (the one on which I was doing the actual fix), I broke the flex band when peeling the volume strip off the glue/sealant/sticky backing (reference about the 4 minute mark of the video). I was doing so well up until that point! So again, be VERY careful whenever working around the volume strip. Even though I got the camera module fixed/replaced, now I have no volume control with my rocker
4. You really only need to remove the daughter board for the camera module replacement, so as others have mentioned in this thread, don't worry about removing the entire motherboard first. You only need to remove the screws/connectors, etc. around the perimeter of the daughter board, and where it connects to the mother board. So basically, you can skip the steps between minute 4:25 and 6:45 in the video. After the step ending around the 7:10 mark, you can move to the 8:00 mark where he starts to remove the daughter board. You can just pull it out from underneath the mother board. He doesn't remove/replace the camera, so you might want to look at the videos in the OP for that part of the process.
That's my two cents on this project. I really do think this video and his process for removing the back case is the best.