OK
did you copy your old BIOS settings before you flashed to the new BIOS / have any pictures on your cell phone to reference ?
 
EVGA Z370 FTW manual PDF
 
 

If its an issue with the BIOS Flash not working, you can
 
Shutdown PC, pull the power from the wall, use the BIOS switch on your MB to go to second BIOS is an option when you have a BIOS issue
 
 
Look at your Manual (link is above) ---> go to page 48 & 49 and Follow all steps
 
(excerpt)
HDD/SSD/M.2Setup

Next, click “Boot” from the menu list at the top. “Boot Option #1” should show the device that you intend to install your operating system.

If you are using a standard SSD/HDD connected to a SATA port, but the device is not present in the Boot Option #1 menu, scrolldown to “UEFI Hard Disk Drive BBS Priorities” at the bottom. In this menu, the top item will be “1st Boot” and will have a pulldown menu on the right. Click on the pulldown menu and select the intended drive; this will make the drive appear on the previous menu. If the drive continues to be missing, please check the troubleshooting section on Page119.

If you plan on using anM.2as a boot device, click on or navigate to the “Advanced” menu, select “Onboard Device Configuration” and enable the portwith your installed M.2 device.

Once this is done, press F10 to save and exit, plug in your operating system installation medium (likely a thumb drive) and Windows 10 should be able to boot to the M.2 without issue.

Additional information to assist with M.2 or PCIeinstallation can be found in the next section.

*Note*Some device manufacturers require specific drivers for HDDs or SSDs (such as M.2) before Windows can detect the drivefor installation. Please make sure to consult the manufacturer’s instructions for your HDD or SSD before attempting to install Windows to determine if additional drivers are needed
 
 
 BIOS Setupand Windows Installation for M.2 and PCIeNVMe SSDs
             -----> follow steps 1- 11

I do not see "UEFI Hard Disk Drive BBS Priorities" at bottom when scroll down and I do not see "Harddisk:Windows Boot M... " at boot options anymore, last that does not try to boot windows that automaticly bring the BIOS screen what is the meaning of this ?

Disable CSM
 

 

It takes the Bios a second boot to see your M.2 and Keep CSM Disabled
On your MB the two bottom needs to be set to Enable (I only have One M.2 Drive)

 
 Set the Bios to use the PCIe Graphics Card and turn off the one on the CPU/MB

Legacy is bit slower, and less secure than uefi.

gomidas

Sajin
Legacy is bit slower, and less secure than uefi.

So this means I did not installed it at "UEFI" mode but "LEGACY" mode before ? Now I went in system information and I see Bios mode is not UEFI but in my language "OLD". Is that possible to convert it to UEFI on running windows10 ?

Yep, and Yes... https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10