Since the day I installed it, my Rift S has done this thing where it might or might not work when I first start my PC. If it does work, it will exhibit this problem after the first session. The headset would display an orange light inside and the Oculus app will demand a restart. After the restart, it would just keep demanding another and the headset would not come alive again. I googled these symptoms and found a couple of proposed fixes, neither of which worked. I had decided to just live with it, but I then discovered that the righthand Touch controller was also dead. I replaced the battery, but it was still dead. Not mostly dead - all the way dead.
I decided to return it. I took everything off of the PC, removed the batteries (they were brand new, after all, and the missus watches every penny I spend - more for her that way, I suppose) and boxed it all up. Flagged it as a Return on Amazon. They were to pick it up tomorrow. Figuring I had a long Sunday to get through first, I decided to just use the headset for the rest of the day. Lo and behold, it worked perfectly! No sign of the previous problem. A little later, I got curious. I put the batteries back into the Touch controllers and.... it all still worked! It has been working flawlessly ever since. I'm going to give it a few days to be sure, but it looks like it's going to keep going.
I saw quite a few other people having this same problem - I hope this posting helps them too.