Water and dust are no match for this huge USB drive which adds 2TB of external storage to your computers, tablets, consoles, ...
This enclosure features some means of connecting the hard drive to your computer or another device, usually a USB port, and may also (depending on its size) have some sort of power adapter.
(1) An external storage or optical disc drive that plugs into the USB port. See portable hard drive. (2) A small solid state storage module that plugs into the computer's USB port.
If either of them is not connected well or loose, the BIOS won’t recognize the drive, and the computer won’t be able to use it for booting. Boot into the BIOS and check the boot order.