When you say you work on your machine blind, I'm assuming you mean you have it connected to an external display? If so, and that works, then that means the video chip and logic board fine, and the problem resides either with the screen itself or the screen cabling.
If a flashlight shone through the Apple from behind does not reveal a faint image (i.e. indication that the backlight is dead), then that would point to either the screen itself being dead, or the video cable being flaky. I would not suspect the inverter cable, because if it was at fault you'd probably see a faint image. My first step would be to pop the topcase off, and verify that the video cable (on the right side of the logic board) is fully seated.
My next step would be to replace the whole screen assembly (casing, screen, cabling, and hinge) with another that you know is working.
If you want to go to the effort, you can disassemble the screen casing and first try replacing the video cable, and the screen itself if necessary, but the Aluminum screen enclosures are very hard to work with, and, again, my preference is to save time and agony by just replacing the whole thing, although like I said, others will disagree.