I would lean towards it being a screen issue. Unfortunately, you can't know 100% until you try replacing one of them.
I would recommend replacing the screen for multiple reasons. Firstly, screens are typically broken by being dropped or another form of physical trauma, which is what happened here. In my experience, backlight fuses typically fail due to liquid damage or power issues.
Secondly, replacing the entire lid has less risk. If you pick a good listing for the lid, you have the option to return it and only be out some shipping money, whereas if you replace the backlight fuse needlessly you run the risk of destroying the motherboard.
Let me know if you have any questions!