Windows 10 HDD clone not bootable

Hi there,

I have a Windows 10 Alienware R7 desktop and I had my operating system on a SSD drive. I cloned the Windows OS to a 2TB HDD that is also in my desktop because I would like to dual boot Ubuntu and want Ubuntu to be installed on the SSD instead of Windows. The tool I used to clone was AOMEI Backupper Standard. As many others, I am unable to boot from the newly cloned HDD drive in the UEFI. I have both drives in the computer because it came with it and I don't want to try to disconnect the SSD because I don't even know how. When I try to change the boot order in the UEfI it only says bootable media; this is connected to the original Windows OS on the SSD. I was hoping to see different drives to select but I don't.

I've read so many threads that all say different things and I think it has to do with the EFI not cloning properly or something like that. I have no clue what to do but I think that the fix is something with diskpart, FAT32, assigning a letter and mounting a volume; not sure though because I don't know which partitions that should be done to. I tried to make the HDD system partition "active" but then I got an error about needing to change the disk to MBR. I read that some people suggest changing the disk from GPT to MBR but I don't think this is my case because my computer has UEFI and my original Windows 10 installation boots from a GPT drive so I don't think I should be changing it; seems like I should if I had BIOS.

I am completely lost and have spent 2 days trying to figure this out. Here is a picture of my disk management. if anybody has the answer that would be awesome.

Solved my problem.

The bootable media on the cloned drive is hidden (it's EFI System Partition which is labeled ESP in the second image). As seen in the second image, there are 2 of the ESP and one is hidden and the other is system. To make this discoverable to the OS do "command prompt" in search and right click and select "run as administrator"

run these commands
`diskpart`
`list volume`
now find and volume which is an ESP and is also hidden. In my case it was volume #2
`select volume hidden_volume_number_here`
`assign letter=S` # you can choose other letters that aren't being used if you want
`bcdboot letter_you_chose_here:\Windows` # this allows window to make the previously hidden ESP visible and marks it as to be discovered
`exit`

restart the computer and get into UEFI by constatnly pressing certain button at alienware logo during startup. In my case I press F12.

Click boot tab and the other cloned disk is now available to be booted from under the boot option.