Macbook Pro not detecting bootable USB with Yosemite

I created a Yosemite boot USB, from the App Store version 10.10.1.

When I hold option during Boot, the USB drive doesn't show up on the menu.

I have an aluminium MBP, bought in 2009. It is the full body aluminium with the Superdrive.

Per Apple, this is my machine:

MacBook Pro (13-inch, Mid 2009)

The only drives I see when holding down option are Macintosh HD and Recovery. When I try to run recovery, it runs for a little and then goes to a "no" symbol, with the spinner still spinning. I am concerned that the HD may be dead/dying, but I don't want to jump to that conclusion yet.

How do I either boot to my USB, or just get a restore done?

I have already successfully backed up my files. I just want to restore the machine.