New firmware updates often reset storage controller modes. If you receive a "No Bootable Device Found" error, enter your BIOS settings and toggle between UEFI and Legacy/CSM boot modes to match your original operating system installation configuration.
As soon as the screen goes black and begins booting up, repeatedly tap the key or the F2 key. (AMI firmware natively maps to these keys, though some systems use F1 or F12). American Megatrends 4.6.5 Bios Update
If you are updating a laptop, plug it into wall power and ensure the battery is charged to at least 80%. If you are on a desktop, connecting to an Uninterruptible Power Supply (UPS) is highly recommended. Step-by-Step Installation Methods New firmware updates often reset storage controller modes