I wiped (all partitions) a MacMini without knowing it was running bootcamp. This caused it to go to a Windows screen that said "no bootable device" when I used cmd R during boot to select a DVD or USB drive to boot from.
I got rid of that error with an NVRAM reset but...
Now, if I insert a Yosemite install DVD and use cmd during startup to select the DV, I hear the DVD spinning and the Mac sits at a white screen.
I created a Yosemite USB installer, it does the same thing as the DVD.
I also created a Lion Recovery USB, it does the same thing, white screen.
What else can I do to install OSX or to install a recovery partition to install OSX?