Mid-2012 MBP Bootcamp Installation I have been trying unsuccessfully for the past few days to install Windows 10 on my mid-2012 15&quot; MacBook Pro.  I've read a few different sites (including this one), but I am just struggling to parse the information into something that has proven useful to me.
I downloaded the latest ISO from the Windows 10 site (October 2020 update).  I went through the Bootcamp Assistant prompts - mounting the ISO to a 32GB flash drive, downloading the Bootcamp drivers, and creating the partition (200GB).
The MBP critical information is as follows:

Mojave 10.14.6
1TB SSD
DVD Drive recently not operating correctly (still need to
troubleshoot)
No USB devices plugged in besides flash drive with mounted ISO

When I reboot after Bootcamp Assistant is complete, I hold down ALT and am shown three options: my OS X partition, my USB drive, and EFI Boot.  I select EFI Boot.
I then go through the motions, entering my product key etc, after which I am confronted with a screen with the partition selections.  Of course, I cannot choose the option OS X has created for Bootcamp because of it being recognized as MBR instead of GPT.  I used GPT fdisk (had some trouble with rootless system but was able to get past that by disabling in recovery environment) and received the following message:
Warning: Devices opened with shared lock will not have their
partition table automatically reloaded!
Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

This indicates there is nothing wrong and it is indeed a pure GPT partition table, no?  Either way, I thought so, so I went back into OS X and deleted the Bootcamp partition in Disk Utility and manually re-created another partition to use.  I got my inspiration from this article and was able to get back to Windows Setup within EFI Boot, delete the partition within that environment which I had created manually earlier, and then create a new partition with the newly unallocated space.
After this, it begins the process of installing Windows.  Unfortunately, the joy does not last long because I end up with a BSOD, followed by multiple reboots where I have the option to try to &quot;recover.&quot;  This results in more BSOD's and a loop of involuntary reboots until I hold down ALT and tell the computer to go back to OS X (with my head hanging in shame).
I'm at a loss as to what to do next here.  Right now I am downloading an older version of Windows 10 in the background to see if perhaps it's an issue related to that.  This guy seems to believe an older version of Windows is necessary in order to have success.  We'll see.
As others have noted, it's not possible to boot from the USB directly as the laptop simply comes up with a black screen indicating there's &quot;no bootable device, press any key, etc.&quot;  This would certainly be the preferred method if it were possible.  Any help is appreciated!
EDIT:  Here is a post outlining the exact place I am at.  The thread indicates USB3.0 drivers are the issue now.  I'm prepared to start over and track down the necessary drivers to add to the appropriate folder in my flash drive, but I'm now starting to wonder if there's any other steps I need to be aware of before I run into potentially the next road block.
I would seem to me that you are missing the obvious. If the Boot Camp Assistant configured your Mac to install Windows 10 to BIOS boot, then you should have not tried so hard to defeat this. Install Windows 10 to BIOS boot and if this works, then accept that your model is one of the last built before Apple converted over to UEFI booting Windows 10. From my understanding, the industry switched to UEFI booting Windows in 2011. Apple, which usually is forward thinking in technology, eventually lagged behind and did not convert until sometime in 2012 or perhaps 2013.
I do not understand how the Windows installer detected hybrid partitioning while gdisk did not. You may not have applied gdisk to the correct drive. Using the Disk Utility or diskutil command to remove and recreate the Windows partition would under Mojave eliminate any hybrid partitioning. This would then allow you to attempt to install an UEFI booting Windows 10. However, if Apple indented for you to install Windows to BIOS boot, then the Boot Camp drivers may only be designed for BIOS booting. This may account for your BSOD issues.
There was a previous version of Windows which caused the BSOD to occur due to the version of Boot Camp that was installed. This problem could be resolved by manually upgrading BootCamp or by installed an older release of Windows. Although you did not specify if your BSOD problem occurred before or after installing Boot Camp. Also, there does appear to be previous versions of the Windows Support Software for your Mac which can be downloaded.
Installing Windows 10 by BIOS Booting the Installer from an Internal Drive

Here, I assume the internal drive is hybrid partitioned. If not, then use gdisk to create hybrid partitioning. The gdisk commands are given below.
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Use the Finder application to rename the file AutoUnattend.xml in the root folder of the flash drive to NoAutoUnattend.xml.

If the volume label of the flash drive is not WINSTALL, then use either the Finder or Disk Utility application to rename the drive to  WINSTALL.

Restart the Mac and hold down the option key until the Mac Startup Manager icons appear. Select the external drive icon with the label EFI Boot to UEFI boot from the flash drive.

When the first window appears as shown below, press the shift+F10 key combination. A Command Prompt window will appear.


Enter the command given below to execute the disk partitioning application.
diskpart


The diskpart command is interactive. Enter the command below to list the current volumes.
list volume

Enter the next two commands to change the drive letter for  the WINSTALL volume. Replace # with the volume number for this volume.
select volume #
assign letter=p

Enter the next two commands to change the drive letter for  the BOOTCAMP volume. Replace # with the volume number for this volume.
select volume #
assign letter=w

ExFAT format the BOOTCAMP volume.
format fs=exfat label=BOOTCAMP quick

Make sure the the BOOTCAMP volume is the BIOS boot volume.
active

Exit the diskpart command.
exit


Copy the files from the flash drive WINSTALL volume to the internal BOOTCAMP volume.
xcopy p:\* w:\ /e /h


Prevent the internal BOOTCAMP volume from UEFI booting from the Mac Startup Manager.
ren w:\efi noefi


Install the BIOS boot code to the internal drive Master Boot Record (MBR) and the BOOTCAMP volume.
bootsect /nt60 w: /mbr


Close the command prompt window.
exit


Click on the red box with the X as shown below, then select the OK button in the popup window. When the Mac restarts, hold down the option key until the Mac Startup Manager icons appear. Hold down the control key and select the internal drive icon with the label Windows to BIOS boot from the internal drive.


Enter the following command to get the drive letter for the WINSTAll volume.
echo list volume | diskpart


Start the Windows GUI installer to install Windows from the flash drive. Windows will be installed to BIOS boot. If the drive letter for the WINSTAll volume is not E, then make the appropriate substitution when entering the following command.
setup  /unattend:E:\NoAutoUnattend.xml


When you reach the window shown below, highlight the partition with the BOOTCAMP label. Click on Format, then the OK button in the popup window. When finished formatting, click on the Next button.