I then made sure all other video configurations were once again commented out.
Guess what? Didn't work. My TV is still just as dark as the first day I tried this out.
I'm going to re-image again. I know this specific flavor of RecalBox for the XU4 is a fork and y'all probably aren't the best folks to reach out to when I'm running your OS off of super-specific hardware, but jesus it's hard to find sensible documentation.
@playpixel I have nothing against the BETA version, I recommend it here in the forum for many people, and most of the people who tested it had their issues solved.
I use the latest stable version (18.07.13) because I have a "normal" Rpi3 (it's not Rpi3 +), and everything is working fine, it's not worth it for me to switch to the BETA version, since I have no problem.
If it is to recommend a version for you to install, I recommend that you use the BETA version (but never update it!), If you did not like BETA, use the latest stable version 18.07.13.