From the boot menu list, select your USB drive. If your system is UEFI-based, select the option prefixed with "UEFI:".
Macrium utilizes the Windows Preinstallation Environment (WinPE) or Windows Recovery Environment (WinRE) to build the ISO. macrium reflect iso bootable
Select (or click the disc icon on the left sidebar toolbar). Step 2: Choose Your Architecture and Environment From the boot menu list, select your USB drive
Complete Guide to Creating and Using a Macrium Reflect ISO Bootable Rescue Media From the boot menu list
In this moment, the backup files stored on your external drive are useless—because you cannot run your backup software without an operating system. This is precisely why the environment is the single most crucial component of any robust disaster recovery plan.