irrelavent. removed

irrelevent. removed

Conclusion:
-----------
After some trial.. I am more convinced that it has nothing to do with older hardware, totally to do with software issue.
Just to conclude this thread instead of abruptly put it as "solved" , just to discontinue this thread. out of good will.

Side question:
-------------
what is the thing that boots up linux livecd (the one that detect whether legacy boot or uefi mode, [the module that responsible to detect and decide] ? is it "bootloader" ? or grub ? I am trying to locate a proper word to use instead of mislead the reader with random word.



I believe it was the windows partition issue, somewhere messed up (MBR or there might my /boot/efi folder in the sda1 partition), that causing linux "bootloader" to think it should uses EFI to boot up.

I have tried over 10 times of reinstalling or boot up (trying to install) with EOS liveus, it just went straight into EFI mode instead of legacy (remember: My hdd boot sector is MBR) , hence causing problem in the installation.



NOTE:
------
I have downloaded 2 SUPERGRUB2 ISO:
SuperGrub2 "hybrid" (for UEFI & Legacy boot) (which is recommended for everyone said on the website) and
SuperGrub2 "for legacy only"


This is why I came to my conclusion
-----------------------------------
Using "SuperGrub2 hybrid iso" to boot up the pc to win7, it prompted error:
But when used
SuperGrub2 "for legacy only" iso to boot the same pc up to win7, EVERYTHING WENT FLAWLESS, landed in win7.







==========================================================================================
Overview of My system [Repeated info: just so that the reader under stand the system setup]
-----------------------
*bios setting:
CSM = on (apart from this CSM button, there is not any efi or legacy related button in the bios)

*only 1 Hdd ( MBR):
Preinstalled with win7.
sda1 win7 reserved
sda2 win7 ntfs
sda3 ext4 /
sda4 extended
sda5 swap
sda6 ext4 /home

*liveusb:
latest github endeavouros liveusb
burnt with latest rufus (chose MBR mode in rufus before burn)
=========================================================================================

i've booted Linux from a boot USB that has grub since I had a motherboard that could boot from USB (which is just 2 years ago!) (grub on the thumb obvious has a config that points it to a non-bootable hard drive partition)

i advise you not make a dual boot, or boot linux from a usb if you must, because: it's simpler

In your first post the pictures show the word efi is seen indicating you booted the usb in efi mode.
What ever key you have to press when first turning on the system to change boot order in order to boot the usb with bios, not bios setup, when you get a menu of options to boot, select the one for the usb that doesn't have efi in the name.

I have my own laptop that have dual boot win7 and arch, which is working fine.

This issue comes with another laptop , which belong to a girl who need to use win7 as her work required. To let a person who never use linux before, straight dive into linux is let her drown. She won't able to do her work.

Also because i have not master the way to install the required software for her to type.. which is language input method. She does translation work fr audio recording..
Thats why if i don't do dual boot, her work will be hindered.
If i don't install, she will never able to switch to linux.. not in this life time. Her windows has got all these weird issue.. trojan issue.... licensing issue... pissed off already.. hence want to change.

This computer of her... somehow got this weird problem that linux boot up thinking it is UEFI.. even when the primary hdd is in MBR (win7 installed first). This is the weird part of the problem.

I used supergrub2 disk that have both UEFI and Legacy capable, when boot up this weird laptop, it just boot into UEFI and got stuck.. Since it has the capability of boot into both legacy and UEFI, why it chooses UEFI since the laptop hdd is in MBR ?
That's the weird part that i would like to know why. I would like to know what is the reason, and how to get rid of the thing that causes liveusb to decide to boot in EFI instead of Legacy on a machine with MBR Hdd.

I have tried to do your above mentioned .. but there is NO such option available.
I tried F12 (fujitsu boot menu selection), there is no such option to choose.
I tried grub boot menu, there is also no such option to choose.
You got to believe me when i said i tried it.. because i have indeed tried it many many time. I have asked several forum.. many ppl suggested what you have said.. but there is not NONE such option.. That's the weird part. Even the linux distro forum don't believe when i said that. But that's the fact.. That's why i think there is something in the Laptop hdd that causes such issue on boot liveusb. And i would like to know what did grub looks for in the HDD that draws such a EFI boot decision..