Hi. I changed my cracked screen and damaged LCD (Mac Pro 2011). Followed YouTube guide to change screen. Now when I turn it on, all that happens is the fan runs and no start up noise or images. I noticed some sparks from the LCD cable when I was trying to plug new one in, but had disconected from the back board ( to get the slack). I didn't disconnect battery as YouTube didn't advise. Have I fried my logic board????