Need some serious help please guys. My Mac Pro has bricked itself after a failed Windows 10 installation through BootCamp. Went through all of the correct steps within BootCamp. Process appeared to be going well until the very last moment when a pop up box appeared stating that the installation had failed due to Error XXXXXXXXXXXXX. Both internal drives have been f'd. There is no sign of OSX on either of them. Cannnot boot from DVD or USB. Time machine back ups are not GUID based so no recovery partition to work from on them. I have tried all the possible keyboard short cuts, Cmd C, Cmd X, Cmd Alt R, Cmd R etc. Nohing is working. Cannot see the startup manager either. It appears that all evidence of Mac OS X has been erased from the computer. After spending all night trying various methods I have managed to get XP installed on one of the drives. Have installed all of the boot camp drivers etc required for that to work. Sadly, BootCamp 3 cannot boot to external copies of Mac OSX. Cannot force BootCamp to start into Mac OS as it cannot detect and Boot drive to go from. All I get is a white screen. or grey screen with flashing white cursor. Depending on which key combination is pressed. Going to an Apple Store in the morning see if they can dump Mavericks or Yosemite onto a hard drive for me. Would appreciate any advice before hand though.