Windows 7 impossible update ? Computer shutting down

Florent_1

Prominent
May 27, 2017
1
0
510
Hello,
I am experiencing some troubles since I tried to update windows 7 on my DELL latitude e6420 :
I bought it yesterday from a friend, the computer wasn't used for a while, when I first booted, a big window came up "Your windows' 7 version is obsolete/deprecated, please update to service pack 1" (Something like this, the message was in French, so I don't know the exact english vesion).
I then tried to use Windows update tool. It did work until it said "Windows needs to reboot ..." -> Reboot now.
On computer reboot, it is somehow stuck on "Windows configuration step 1 of 3", and the computer shuts down after a strange grey/white screen :

https://img15.hostingpics.net/pics/978037Screenshot20170527103815.png

Here is what i've tried so far :
1) Rebooting 3-5 times .. ( No effect )
2) Going to the bios, trying to boot on nothing, then going back to boot back on HDD (no effect )
3) Booting on UBUNTU Disk to install Unbuntu and get rid of windows ( Same shutdown, same white screen ...)
4) Booting on Repair disk ( previously downloaded ) No effects (Same shutown, same White screen )
I've tried some other solutions such as renaming system files to xxx.old etc.. But none worked.
I suspect a physical problem, but I am not aware of what it should be.
I was wondering if I could HARD RESET everything thanks to the bios ? (The Dell latitude e6420 bios looks awfull tho, not the kind of bios i'm used to see)...

Can someone think of any solution ? I have no ideas left :/
I can try solutions and post results with pictures (thanks to some smarthphone because the computer won't boot on safe mode anymore, just stuck at "Loading file system" and a .sys list on black screen with white fonts)
Thanks in advance !