Help MacBook pro

[Bzerrenner]

Got a Mac Pro on Craig's list for 100 bucks guy said it was stuck on Apple screen . I put yosemite on a flash but holding option s is not working ? Can I boot the usb from the root it's the only screen I can get to ! Thanks

 

[Bending Pixels]

Kinda sounds like the motherboard is toast. You paid $100 for a doorstop.

 

[DeltaMac]

Got a Mac Pro on Craig's list for 100 bucks guy said it was stuck on Apple screen . I put yosemite on a flash but holding option s is not working ? Can I boot the usb from the root it's the only screen I can get to ! Thanks

What do you expect Option-S (nothing should happen during boot holding Option-S)
I guess you mean just holding Option. You should see the various boot drives, and you should be able to select the boot drive for the Yosemite USB flash drive. If you don't see it in the Option boot screen, then maybe it is incorrectly prepared (and is not bootable) Did you try it out on a different Mac?
Is your MacPro capable of booting to Yosemite? You need a 2008 model or newer to do that natively.
An older model (2006 or 2007) won't boot or install Yosemite, unless modified with an acceptable graphics card, etc.

 

[maflynn]

I put yosemite on a flash but holding option s is not working

Hold the option key only down, that will bring the boot menu up. cmd-s bring up single user/verbose mode.