Struggling to install Ubuntu 20.04 LTS to newly built PC

Sorry, I meant that I was booting to a GNU Grub, not a grub menu. Are you thinking this is something to do with the moderboard, perhaps a BIOS setting I'm missing or something? I could always just replace the motherboard...

If you are getting grub> can you manually boot?

First try:
configfile (hd0,2)/boot/grub/grub.cfg

Or:
set prefix=(hd0,2)/boot/grub
set root=(hd0,2)
linux (hd0,2)/boot/vmlinuz root=/dev/sda2 ro
initrd (hd0,2)/boot/initrd.img
boot

When I woke up today, I booted into the hard drive without the USB in the computer, and it booted into Linux successfully. I have no idea why it’s working now. I’m skeptical really. Is there a way I can confirm that the installation is complete? Or if I need to finish it manually? Also, if I put the windows nvme back in the computer, could I just boot into Linux and update grub for dual boot? Thanks!

I expect you can plug in Windows NVMe and update grub.

Only issue may be if drive 0 & drive 1 get changed. Not sure how two NVMe drives are ordered in UEFI.
With SATA it is port order and sometimes that makes a difference. And some NVMe drives can conflict with SATA ports.

I was able to make it work. Can now dual boot as I desired. To be honest -- I'm not entirely sure what the solution was to this problem. But, I'm glad it's working. Thanks for all your help @oldfred

Took a bit, but glad you got it working.

Laptop: Lenovo Flex 5 (how I gave up UEFI and lived to tell)

I worked for over a year trying to install both Mint and Windows on my laptop (had a working laptop before this one but wearing out my second keyboard after 4 years of use, I bought another laptop) and finally got the new one working yesterday. I was holding off moving to the new laptop until I could figure out how to install both Linux and Windows fairly seamlessly and it took me over a year working here and there (as I regained my patience) to finally get it working.

- download fresh install of Windows 10 from MS (registration for Win on my laptop is in the bios)
- backed up photos, documents, etc from small work I'd done in Windows
- purchased EaseUS Partition master to create a USB bootable WinPE ISO with PM on the drive
- used Rufus to create GPT formatted USB stick to install WinPE USB bootable copy of Partition Master
- used Windows UEFI interface (via Windows settings) to boot from the USB stick (only way I could make laptop boot from USB)
- used EaseUS to convert the GPT formatted SSD on the laptop to MBR
- struck F2 after restart to change BIOS secure boot off and change storage setting from raid to non-raid for storage option
- also change BIOS type setting from UEFI to Legacy
- used RUFUS to re-format all my USB bootable thumb drives from GPT to MBR
- used EaseUS to delete all partitions on SSD and create a single NTFS for Windows 10
- used EaseUS command line (with Win 10 on another USB drive) to install fresh copy of Windows 10 back on the drive
- used EaseUS to create an unallocated space just beyond where the Windows partition was by stealing some space from Windows
- used USB bootable thumb drive (Rufus/MBR option) with Mint on it to install Mint on the unallocated space
- now the Linux boot manager (forgot the name, Grub or something like that) to choose windows or Mint
- downloaded the GUI "app" version of the same boot-manager "manager" and changed default boot to Windows
- so far so good

Do not recommend MBR(msdosl) & BIOS boot, but if it works for you that is ok.

GPT Advantages (older 2010 but still valid) see post#2 by srs5694:
http://ubuntuforums.org/showthread.php?t=1457901 &
https://wiki.archlinux.org/index.php...antages_of_GPT
http://en.wikipedia.org/wiki/Unified...ware_Interface
http://askubuntu.com/questions/62947...br-why-not-mbr
UEFI Advantages
http://askubuntu.com/questions/64730.../647604#647604
http://askubuntu.com/questions/44696...y-vs-uefi-help
http://en.wikipedia.org/wiki/Unified...ware_Interface