I put the dm 2.6 and wad manager 1.7 wad in the "wad" folder on my sd.
I used homebrew channel to open wad manager. I chose ios 236 at the first screen and then installed DM 2.6.
I went to boot a game that works with my thumb drive and get a splash then black screen.
Note: I've had usb loader gx set to use ios 249. It's been working with the thumb drive this way. Just now, I tried changing that to 236 but it didn't change the outcome. Oddly, when I do that and then reboot the loader... the ios has changed that to 222 all on it's own.
It's all a tad above my head yet...
I've tried it with a disc in and without.
My loader has been set to use 0 usb port. I've been plugging into the bottom port (if the Wii is laying flat.)
Edit 2: yes, the main gamecube path is usb1, and always has been.