Black stripe on my Sharp Aquos Tv screen

Yesterday I had to remove the back lid of the screen to Unplug the Power cable from the inside. After putting all the pieces back together (screws and lid)I noticed that a black vertical stripe roughly 3cm large has appeared on the right-hand side section of the screen. Today I opened the posterior lid one more time to check whether the connections were fine and they appear to be properly plugged in without any damage. Does anyone have any idea of what the cause could be and if there is a solution to the problem???