White Screen...

Hello. I turned my iMac on and all I get is a White Screen.

I have searched the web looking for answers, and nothing has worked. I have tried the following:

PRAM reset (cmd, Option, R and P) (even tried a Shift, Command, R P combo I found somewhere)

Command R

Plugged an external monitor in (via a MiniDVI to VGA cable)

Removed Hard drive, and tried a brand new blank one (to see if it would prompt an OSX install)

Nothing has worked...

Please help. I am out of possible ideas at this point

Thank you