Acer aspire s7-392-9439: default boot device missing or boot failed.

Hi,
I bought an Acer aspire s7-392-9439 3 months ago. It's been working great, until yesterday.
I turn on the computer and it poped a blue screen with the error: "default boot device missing or boot failed".
This error reminded me that a message about a bios update poped out a few days ago and I diden't get the chance to install it.

I've contacted acer support, they told me the bios update would have prevented this problem. Also, they told me to try some stuff that may help, but unfortunately none of them did:
1. Restoring the bios settings to default.
2. Changing bios settings: uefi to legacy.
3. Tapping winkey+c on computer boot.
4. Creating a USB DOS bootable media gets me to a cmd line, but when I call the isST2212.exe it popes: "This program cennot be run in a DOS mode".

When those options failed they told me it's probably a hardware problem and I should send my computer to thier repair center.
My questions are:
1. If they bios update would have prevented the problem, how can it be a hardware problem?
2. Does anyone know how to fix the problem?

I would really appreciate your help,
Michael