hey all,
one common reason for having black screen is not having the nintendont config setup. this can be solved by booting nintendont by itself, select the settings you want (if using wii u injects, i believe you need to at least set autoboot to on). i also use separate memcards for each game and wii u widescreen. then boot at least one game from the "games" folder for the settings to save. uwuvci can also create this file for you on the gear setting in the top right corner
one this is done, you can go back to the wii u menu and your injects should work.
for injects, as long as you have the latest version of uwuvci with rhythm heaven fever base and .net framework 6 installed, your injects should come out ok. i would also consider installing the visual c++ all in one installer from majorgeeks and python sdk, just because some other homebrew apps may ask for these things as well. you should also be installing your injects to an external hard drive, either with y-cable or external power
speaking of hard drive and SD card, i use an endurance sd card for longevity, and a sata ssd drive in an enclosure.
it's the following:
endurance sd card from samsung or sandisk (i switched from 64gb to 32gb to be fully compatible with some other wii homebrew, but get at least 64gb so you can backup the wii u nand)
https://a.co/d/aWjxI4c
samsung 870 evo sata ssd 1tb refurbished (or new if price is good) from best buy/amazon
https://a.co/d/iVIKkd4
ugreen usb 3.0 enclosure for 2.5" drives (NOT the usb-c enclosure, the traditional slim usb 3.0 hard drive connector)
https://a.co/d/4dAaesv
cable matters usb 3.0 y-cable
https://a.co/d/gnQ3F0y