I am working on a 24" A1225 iMac...it needed a logic board. Put a new board in it, HDD has been wiped and prepped with OS X Installer (I've tried both Yosemite and El Capitan). If I let it boot "normally" I get to the grey Apple screen, the progress bar gets to about 30%, and it stops. After a couple of minutes the computer audibly says "To use English as the main language press the Return key." Nothing further, even I press the Return key. After a few minutes the screen will go black (assuming it's going to seep, but can't wake it up). If I try to run an OS X installer from a USB drive, I get the same result. Even purchased a new HDD and got the same result. The only startup key combinations that work are single user mode, verbose mode, option, and reset PRAM. Any ideas? I really want to get this back up and running so I an get it back to it's owner.