So, I decided to replace the 500GB hard drive on my 21.5 inch iMac (2010 model), and upgrade to a 2TB. I bought the hard drive, got the guide from ifixit.com to install it myself and went to work. I popped it open, followed the directions exactly, and everything went fine. Then once I replaced the hard drive and closed up the iMac, once I turned it back on the screen was black. It started up, made the start up chime, sounded like it was working fine, but the screen just won't come on. I've gone back and made sure all 4 wires that attach to the screen are connected, and played around multiple times plugging them in and making sure they are all correct. But every single time I turn it back on the screen won't work! It's frustrating. Does anyone have any idea what's wrong here and how I can fix it?