Replacing LCD but screen lights up only at initial power-on

I have a Galaxy Grand Prime G530T1, and my Digitizer had broken, and while repairing it, I noticed the polarizing film was starting to peel at one corner and decided to go for a LCD replacement also. I work in Aerospace and have an extensive engineering background, though I haven't worked with phones for a while. Anyways, on to the comedy... I put the new LCD in without the Digitizer and it worked great, but then I managed to drop the phone (sans digitizer) and the LCD refused to ever turn back on,,,, The Second LCD worked fine with just the LCD, but didn't work after attaching the digitizer, and I traced it down to the connector not wanting to "click" in easily, and sometimes it took 15 min to get that satisfying click and for it to work, by which time the digitizer would have freed itself from the chains of the LCD :) At one point, some of the Digitizer Adhesive had connected with the top of the LCD (as it shoukd, though not when I had wanted) and while gently seperating a 2 mm line of adhesive, the very top of the lcd, where the connector sits, cracked..... So, now on LCD #3 (I really was having a bad week with 0 sleep prior to all this fun) The new LCD backlight kicks on when I power on the phone for about 5 seconds, but has nothing on-screen, then goes black for good until I reboot, though the phone works great and have verified it with a remote desktop app (didnt test digitizer connector yet). I have reseated the connector MANY times and no luck. I am using cheap replacement LCD's from Amazon, but am running into a time issue. I'll grab another LCD as this one is probably dead, but I am curious to know if this might be a simple fix since the backlight does turn on? Could it be a bad capacitor on the LCD, or something that I could fix with a soldering station quickly, or with a secret connector tightening trick, rather than waiting on another screen?