I had the same a few weeks ago. I had to do a reset with all data and files
saved. I called Microsoft help.
They were wonderful. .
Was on a queue and got a call back.
I talked to first person , and she put me on hold while she connected me to a Technician. He talked me through the whole process. He said it has been the only way to get you out of S mode. They are not sure why. It worked all is good now.
The simple way supposedly from the Microsoft store would not let me do it.