So I already knew it was a hard drive problem, looked it up, bought a new hard drive. Installed it, screwed the thing back together and pushed power. But it still says no boot device available.... except if u hit the reboot key, it'll jeep telling me that along with a small flash of the Alienware logo as if it was booting up. I don't know if this matters but it also says SAT 0 is installed...

Listen, I'm not extremely tech savvy, and I've been waiting for this hard drive for a long time. Is there something I'm missing or did I make a bad purchase?