well you need a windows key.

 

well you didn't specify if you had a windows key, also when you backup all the stuff, use diskpart to clean hdd and than do a clean install

 

Hello?

 

You can format you hard-drive from the windows 7 installer when you select what disk you want it installed on, below there is some text with some images click the eraser and the disk will format then install you should get no errors

And if your installer does not ask for a Product Key then you don't need one yet

 

Use the Windows USB/DVD Download Tool to install the Windows 7 ISO you already have to a thumb drive so you know that it's bootable. Boot your computer with the thumb drive and run a clean install. If you have a key, input the key during the installation process. If you don't have a key, skip it and use a loader to activate Windows 7 later.

 

ok well, in your video, i dont get that window at 1:30 when i boot from usb stick, i get a couple of error message

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but i can access something similar to repair your computer by the bios

 

windows failed to start. a recent hardware or software change might be the cause

 

sounds like that or hardware is damaged.

 

How did you put the iso on the usb

 

he should use either the offical ms tool or rufus.