Hey I dunno if you fixed your problem with the black bar with Nintendont, but I figured it out. You need to run a Gamecube game through the disc channel. I had Dios Mios installed when I did it, so I don't know if that will affect you. (Dios Mios was having the same problem too)
Caller -"Everytime I start a Pc game on my S24, playing on a external monitor, someone calls or texts me, n it kicks me out of the game." Customer Support - Click (hangs up)
I found it funny cause many many years ago, had a roommate in college that did this same dumbass branding of the school logo, but it didn't look anything like it after it healed. Just looked like a birthmark.