hey guys, hope someone on here can point me in the right direction. i have a 2011 21.5 iMac that i just added a second sad drive to and when i put it all back together and start it up only 2 lights come on on the logic board and i get a single beep. if i unplug the lcd thermal cable then start it up i get chimes and dvd drive winds up, 3 lights on the logic board but no screen. is it just the lcd thermal cable that went bad?