I have a Toshiba Satellite P855-S5312 Laptop and the other day I banged into the front part of the laptop(to the right of the mouse pad) and my laptop automatically shut off giving me a quick automatically repairing error and then switched over to "Diagnosing your PC" this would continue for around 10+ hours and then it would switch to a blue screen that said "Automatic Repair your PC didnot start correctly press restart to restart your PC which can sometimes fix the problem. You can also press advanced options to try other options to repair your PC" I tried both but one left me with a blank blue screen and the other left me with a blank black screen. I tried entering bios by pressing all available ways such as shift-f8 f1-12 delete etc... Any help is appreciated I do not want to bring this computer in for repair because I know they will snoop through my stuff and I do not want that , thanks Eric.
If you have a BOOT disk in the CD/ROM, and the BIOS is set to "boot from CD", it should boot the CD.
If that doesn't work disable the Hard Drive in the BIOS, and try again.
The Diagnostics are probably on the hard drive, and not the BOIS.
I've never heard of a diagnostic program stopping you from what you want to do.