Display ribbon possibly faulty

Hi @johnpauldavie

Did you disconnect the battery cable from the motherboard after you first opened the laptop and before starting to remove/replace the eDP (embedded DisplayPort i.e. video) cable between the motherboard and the LCD panel in the laptop?

Try connecting an external monitor (TV?) to the laptop's HDMI port (on the side of the laptop) and check if there a display showing on it when the laptop is turned on. Don't forget to press the F7 (or Fn+F7) key, to switch the display from the laptop screen to the external screen.

If there is a display showing on the external monitor, switch the display back to the laptop screen and then try shining a flashlight at an angle close to the laptop screen and check if you can see any images on the screen at all. They will be very faint so trying this in a darkened room may help to see them if they're there.

If you can see images on the laptop screen, then there's a backlight problem in the screen. This could be due to a faulty backlight power feed on the motherboard (if you didn't disconnect the battery before replacing the eDP cable you could have blown the backlight fuse on the board), a faulty eDP cable (although if it is new then it shouldn't be) or a faulty screen.

If you can't see any images at all on the laptop screen, then this could be due to a faulty eDP cable (although if it is new then it shouldn't be) or a faulty screen.

If there is no display showing on an external monitor, then it may be a motherboard problem or the laptop's not starting and booting into the OS. Try to get into BIOS to see if the laptop's display is working. Press F1 a few times immediately after turning on the laptop. Using an external monitor doesn't work in BIOS you can only use the laptop screen.

Post back here what the results are.