Reboot and select proper boot device or insert boot media in selected boot device and press a key.

Hello. I attempted to update my Alienware Aurora R4's BIOS from A07 to A11 via the use of the exe provided by dell. The download went fine, but when I rebooted I keep getting this message: 'Reboot and select proper boot device or insert boot media in selected boot device and press a key'. I have gathered some information on my PC, although I am unsure how much of it is relevant:

Note the BIOS setup does register as being A11 now.

I have run the ePSA (including the thorough testing) and the PC has 'passed all tests'.

OS: Windows 10

Firmware Version: 8.1.40.1416

Device info:

Sata Port 1  WDC WD10EZEX-7

Sata Port 2  WDC WD10EZEX-7

Sata Port 3 Not present

Sata Port 4 Not present

Sata Port 5 PLDS DVD+/-RW ATAPI

Sata Port 6 Not present

Sata mode: AHCI mode

My system clock was correct, but the system date was incorrect after reboot.

Boot Priority: (I think this may be the problem, but I am unsure as to the exact order they should be in)

Boot mode legacy

1st Boot: USB Floppy

2nd Boot: USB Hard Disk

3rd Boot: USB CD/DVD

4th Boot: Hard Disk: WDCWD10EZEX-75ZF5A0

5th Boot: CD/DVD: PLDS DVD+/-RW DH-24ACS H

6th Boot: Network

Load legacy OROM: Enabled

Note I have two hard drives, recognised by the device as:

P0: WDC WD10EZEX-75ZF5A0

P1: WDC WD10EZEX-75ZF5A0

On the Legacy boot option, these two show up, so does P4, which is the CD/DVD drive. Should there be a P2 or P3? Also, should 'Launch PXE OpROM be enabled or disabled? 

I'd be grateful for suggestions to get my PC going again. Thanks for any support you can provide.