SOLVED. Iphone 6 constantly shutting off and then back on. I put in recovery mode but every time I got past the extracting software stage, I would get an error message. I tried everything on these posts and more for several hours. This includes using two different MAC’s, four different cables, and re-booting home router multiple times. In the end, in a twist of irony, drum roll please, I plugged it in to a Windows machine and I was back up and running in no time. Very odd, I had to use MICROSOFT to fix an APPLE problem. Hmmm, MAC’s don’t recognize iPhone’s but Windows machines do? Both MAC’s wanted me to do a software download to recognize my iPhone but low and behold, kept getting an error message on that too. Funny, I would think it would be kind of important for each OS upgrade on MAC’s that they would include recognizing iPhone’s.