W7 clean install can't boot on E7250

Dear All,

I am having trouble with installing a clean OS on my machine which is Dell Latitude E7250, I spent three straight days to no avail on the issue that seems to be known :(

This is what I did at first:

I downloaded the Windows 7 PRO image from the drivers and downloads section, made a bootable USB drive and booted it, at which point I get one of the two errors:

1. USB boots, shows that windows is loading files, presents a windows logo, opens a nice blue Windows background but the installation menu for Windows doesn‘t show up.

2. Installation menu shows up but then asks for the required drivers in order to read the data from USB.

***Note: installation menu shows up every time if booting from an SD card but then stops at error number 2.

This is the BIOS setup that I use to boot the drive: UEFI is off, Legacy Boot is on, Secure boot is off.

This is the setup that I use for the USB drive: I think I have tried every possible combination of formatting and partition schemes.

I did some research to find that the image provided may not have the required USB 3.0 drivers integrated and followed these instructions to get the right image:

http://www.dell.com/support/article/us/en/04/SLN301133

This extensive tutorial leads to downloading the same W7 image I have already experimented on.

Then I tried to follow this tutorial:

<ADMIN NOTE: Broken link has been removed from this post by Dell>

 

And then this:

http://dellwindowsreinstallationguide.com/converting-your-dell-windows-reinstallation-dvd-into-a-reinstallation-usb/#DeletingtheEIUSB

Both getting one of the two errors described above.

I have also another two points to make:

1. I have another E7250 laptop on which I tested the above solutions and got identical results

2. I have successfully booted other images with different operating systems.

There is another possibility… Dell system detect has to be ON to download the W7 image, maybe the image is specifically tailored to boot only on the exact same machine? And if so… This makes no sense on many different levels. How should I go around it if the system is bricked?