Booting Windows VII On HP 15-DW3125OD Laptop (Pure UEFI, No BIOS) With Flash Boot

First thing to try, boot the affected installation on wmware/virtualbox/hyper-v (or a different physical machine) and do a full windows update, then try to boot it natively.

Early uefi support in w7 was buggy and was fixed over the years trough updates (starting from the "post sp1 convenience pack")

Then try to use a native vhd boot, where the native vhd is partitioned as MBR

If everything fails try to boot using the Clover bootloader (it provides a sane UEFI boot environment even on legacy BIOS only machines)

That said I never use UEFI boot unless I'm really forced to, the four partition limit of MBR partition limit is matter of the past tanks to native VHDs

You can have 50 different OSes installed on a single MBR partition, multibooting them w/o having to fight with UEFI shell and other pointless hassles.

You can backup a whole OS, just copying a single file.
You can boot the same VHD[x] natively or on a virtual machine
You can move a whole OS between two different machines just using a single copy operation and a single bcdboot command.

In short native VHDs are progress, UEFI is not.

 

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Option A

Clone your install on a VHD (not vhdx as W7 doesn't support them.

Use that vdisk on your favorite Hypervisor

run WU until W7 it's fully updated

Then add your vhd as native vhd to your bootloader (you can use bcdboot or the graphical tools Bootice or easyBCD to do that)

Then reboot your physical machine and choose W7

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Option B

Start your actual working OS, clone your W7 installation in a separate partition on your physical disk

Create a VM using that physical partition/disk

Update W7.

Add that partition to your bootloader.

Reboot on w7

I don't suggest this way as it is more dangerous for inexperienced users
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Option C

Clone your installation to a vhd

then same as A

Then clone your VHD to a physical partition then dualboot from there

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There are other variations, but basically that's the process

Not sure if you read what I wrote, but I read what you wrote.

I suggested clover as it is Quick and very configurable, given was initially created to boot Macos on PCs, so it works in wide scenarios INCLUDING BIOS only machines, not EXCLUSIVELY on BIOS only machines

You only need a bootable pendrive to test it, then, if it works for you, it can be installed on the HDD

Try to paste the same question on google, you'll be surprised. As native VHDs are as old as Win 7