Why LCD is not displaying?

In LCD TV panels VGH,VGL,AVDD,VCOM,voltage dropping problem is very common. cause LCD is not displaying.
Why and how is this problem seen? Here are 5 main reasons glimpsed.
Video related to these problem and solution are here
Big size panel repair    • Big Size Panel Repair  
COF connection in LCD screen    • COF Connection in LCD Screen  
Fix LCD Screen by Replacing Scalar IC    • Fix LCD Screen by Replacing Scalar IC  
#ledtvrepair #panelrepair #vcorelc