@jongarrett yes, it could absolutely be the backlight fuse. In a darkened room and with the computer on (check with your external monitor) make sure you have it set to see the desktop. Then disconnect the external monitor and shine a flashlight at an angle against the screen. See if you can still make out your desktop. If so, you know that this is strictly a backlight issue. Since you have a new LCD installed, the issue will be confined to the laptop itself. Could be the display adapter, the backlight fuse or the backlight circuit (never rule out the backlight enable circuit). To get into the details, we really need to know what model you logic board is. Looks like the Lenovo thinkpad e15 gen 2 uses a couple of different ones. Something like NM-D011, NM-C771 etc. are all a possibility. Post some really good pictures of your motherboard with your Question. That way we can see what you see.
For the NM-D011 the first thing to test would be on the eDP connector pin 9 and 10 since that is your bk light on. Looks like this
You okay with working something like this? You do need a good multimeter and a steady hand :-)
To work to get to the motherboard use the Lenovo E15 Gen2 Hardware Maintenance Manual
@jongarrett I just went through my schematics and your board is a NM-D011. First thing to check is the fuse. It's about the size of a fruit fly :-) Board designator is FG01. I marked it on your image. You will need to use a multimeter and test it for continuity as well as power. Multimeter to somewhere in the 30VDC range. Black to ground and Red probe on either end of the fuse. Let us know what voltage you get when your computer is on. Since it is going to be turned on, you do want to make sure you do not shorten out any other contacts with your meter probes. It sounds so complicated but it's really straight forward. Use common sense and you'll be fine.
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