Acer Aspire Laptop... 5733Z-4851... Customer presented laptop with broken screen. Visual inspection showed cracked screen with backlighting. Laptop had been sitting for over a year. Previous repairs included replacement of keyboard due to spill. Removed and reformatted hard drive with no issues. Reinstalled windows and updated to date with no issues. Used external monitor to complete Windows/software installation. Ordered new replacement LCD. Removed old LCD. Visual inspection showed no further issues. Trouble began with installation of new replacement LCD. Problem with plugging in video cable. Replaced Video Cable with new cable. Visual inspection inside of laptop showed no signs of spill residue or other damage. Dark on new replacement LCD. External video showed ok video. Light shined on new replacement LCD showed fine video image--NO BACKLIGHT. Sent LCD back to supplier. Supplier tested their LCD, no problems. Supplier sent another new replacement LCD. They tested the replacement first. Received 2nd New replacement LCD. Installed LCD with no issues. Still NO BACKLIGHTING. Checked Windows (Windows 10 1803)... no change when adjusting brightness -- on LCD or on external monitor. Is this some kind of a motherboard issue. Is there a step I am missing. I have replaced many many LCD without this issue before. Any suggestions ??