No, the usb should not have a file .iso.  It should be a number of files and folders. If you have a spare usb drive of at least 8 GB, use the MS media creation tool to make a Win 10 installation usb.
Hi There, I have to reinstall windows as someone added a password to the generic USER system admin as a malicious act, so I can't make any changes to the computer that involves Admin permission. I got an ISO from Microsoft Support on a USB, changed the BIOS to Legacy etc, incl making sure that USB bootable was ticked but when I tried to boot from the usb, I got the message 'boot failed'. I've tried jiggling various things in BIOS and used every usb port but to no avail. I can't update the firmware (presumably) as it takes an Admin password to make any changes. I also tried Mounting the ISO in the computer but when I clicked the start.exe the admin password was required so no go. I've already spent many hours with Microsoft Support but they have no solution. They say it's a Dell issue that the usb doesn't boot. Can anyone help?   Many Thanks   Ross    
Optiplex 7010 won't boot windows 10 from usb