I'm hoping to find a solution to my ongoing issue with a laptop I received to deploy to an end user. I'll give some context first.

We use MDT to deploy Windows 7 and 10 on machines with 7th gen processors or earlier. The previous technician set up a bootable MDT USB that I use and everything works great. The things I do before running MDT is set the boot mode to Legacy and all is good.

Now, I received a Dell Latitude 7490 with an 8th gen processor and when putting the laptop into Legacy mode in the BIOS, MDT works fine and boots into Windows 10 and finishes the installation. However, when I reboot the laptop, there is no bootable device and going into the BIOS reveals no SSD as a boot option.

I did some digging and see that Legacy boot is going away in 2020 and that UEFI will need to be used. Okay, so I put the laptop back in UEFI mode, enable Legacy Option ROMs in the BIOS so I can select the USB so I can proceed with my MDT process. Everything goes fine until the laptop reboots. After installing the OS, the laptop will reboot like it's supposed to but then tells me there's no bootable device. I go back into the BIOS and see there's no boot option in Boot Sequence.

My question is. What settings, if any, do I need to change in MDT in order for the SSD to be recognized as a bootable device on this laptop? And what are the correct BIOS settings for everything to work?

Just a side note; I did install Windows 10 from a personal USB I had at home. The BIOS was set to UEFI with Legacy Option ROMs disabled. I was able to boot off the USB and install Windows just fine. In the Boot Sequence, "Windows Boot Manager" was shows as a bootable device. But I was able to reboot the laptop and boot into windows just fine. So I think my issue is within MDT and it not being set up correctly.