Hello, I have had this problem for several days and have exhausted myself trying to fix it. I've used all of the internet sources I could find but have been unable to fix it. The backstory is I was reinstalling windows 10 and I stupidly switched it off abruptly. I was given an error message on reboot and followed a guide to editing the registry to restart the download. The download did not restart however, and my windows 10 is stuck in an endless loop of rebooting. I have downloaded a copy of windows 10 and put it onto a USB, but when I try to boot from USB it takes me back to the BIOS. The BIOS are 'Aptio Setup Utility 2011', and don't seem to allow me to change from UEFI boot to LEGACY boot, although the option is apparently there. Any help would be greatly appreciated and I apologize for if this post is in any way flawed but I am in desperation of help. Could someone please tell me why the USB boot is not working correctly and how to make it do so, I am more than happy to reformat the computer but at this moment in time it's useless. The computer is an Alienware x51 from 2011. As previously mentioned the operating system the PC is trying to boot (or install) is windows 10.