Hello, I have the same problem.
Sometimes at random (usually after reboot or moving the tablet) it boot ups to the shell, when I enter the bios the SSD is not listed.
Bypass I found: When I holdown the power button and volume down button for 15 seconds, then release. Power up the tablet and enter the bios the SSD is found again. I can change the boot order and its booting to windows again.
Very frustrating (tablet is just a day old), anybody know a solution or a fix or is it a hardware thing?