В бутблоке, если посмотреть текстовым редактором видно

В бутблоке, если посмотреть текстовым редактором видно имя файла: AMIBOOT ROM
Для начала стоит проверить читает ли флоп эту дискету, подключив его к другому компу.
Ctrl+Home надо удерживать до тех пор, пока не загорится led на дисководе

Instructions for manually initiating Boot Block Recovery from Floppy Disk:
1. Insert the floppy disk with the new BIOS file in the root directory into drive A:. In most cases the file must be named AMIBOOT.ROM for the recovery process to load the file. However, this filename may differ from one product to another. Please consult the system motherboard documentation for more information.
2. Press and hold the <Ctrl> and <Home> keys down while turning the power on. Continue to hold the <Ctrl> and <Home> keys down until the access light on the floppy drive comes on. It may take a few seconds or more before this light turns on.
3. Release the <Ctrl> and <Home> keys. AMIBIOS issues a series of beep codes that indicate that the system BIOS ROM file is being updated. There will also be a progress dialog displayed on the screen after the file has been loaded.
4. When the flash ROM has successfully been programmed, the computer will reboot. Please do not interrupt the BIOS flash process until it has fully completed.