Chosen Solution
I changed the display whilst the battery was left in and the display has stopped working. I’ve tried another display and it’s showing no backlight but an image so I think the backlight fuse has blown. But the original display shows no image, nor a backlight. How can I best diagnose the issue with the display? macOS shows the display as detected (using an external monitor to show displays connected) just no image or backlight.
I would inspect the logic board LVDS connector area as well as the the other side where the cable connects to the display. Both tend to get liquid damage and/or the cable its self is damaged. The loss of backlight is often a symptom from the damage, and now that too will need repairs as well. How about posting some nice picks of the area like this one:
Adding images to an existing question
