Hacking Wii U not loading CBHC/Haxchi

[any1th3r3]

hi there,

i've recently bought a "for parts" Wii U, which initially booted up with a "-5" error at the top left corner of the screen.
i was able to figure out that it was certainly modded, so i prepared a sd card with the required files (i actually modded another Wii U with Haxchi/CBHC, so i took that sd card to try it out) and was able to get the console to boot into Homebrew Launcher.

the issue is, i can't see the CBHC boot screen (no "Autobooting..."), only a black screen instead, and from HBL i can't go back to the system menu (back to HBL everytime), as well as launching either Haxchi or CBHC (to try to reinstall them) results in a black screen.
i've found a similar occurrence over in a reddit thread, however the person only mentioned reinstalling CBHC, which i apparently can't do.

i'm leaning towards the fact that the previous owner did a factory reset, leaving the modified DS VC game missing, leading into that half-broken state.
is there anything i might be able to do here? i obviously don't have NAND backups for this console, so that might be very limiting.

thank you!