One additional step that you can try is disabling USB boot at all on BIOS so the system will not consider booting from USB because the reason why you may experience that is because the system detects the drive and checks if is a bootable device, which may cause that it gets stuck during that process. In order for you to do that you need to follow this steps:
- Get in to the BIOS
- Go to "Boot"
- Search for the USB option and disable it
- Press F10 to save changes
- Get in to the BIOS again and get in to "Boot" again as well
- Check on the boot devices if the external drive appears there (it should not appear)
- Exit BIOS and let the system restart
Please let me know if the suggested workaround solved your problem.
To better summarize, there are two possible reasons for this behavior:
- If the "Boot USB Devices First" option has been enabled, it will always have the problem. Disable this option.
- The boot order could place the external, non-bootable drive ahead of the HDD/SSD. Change the boot order to place the HDD/SSD ahead of the external drive.
Hope this helps...