Replacing the hard drive unsuccessful.

That is expected reaction until you install the OS.

If you still have your old drive and it still works you'll need to put it back in. Then once the system is running prep up a USB thumb drive (16 GB or larger) using Disk Utility to wipe the drive and created a GUID partition map and a Mac OS Extended (Journaled) partition. Once this is done you can then run the OS installer which you can download from the App Store. This will allow you to install the OS onto the Thumb drive. Now copy over to your thumb drive a fry copy of the installer as you'll need to run it again to prep your new drive.

OK, you've prepped the USB drive and you've put the new drive back in, now with the Thumb drive plugged in restart your system holding the Option key this will get you to the Boot Manager to allow you to select the USB drive as your boot drive. Once your system is up and running (remember the USB drive is slower than your SATA drive) run Disk Utility again to delete the current partition on the drive if it has one and then format it with a GUID partition map and Mac OS Extended (Journaled) partition as like before. The last step is to run the OS installer.