Some more progress: doing the old "unplug and hold the start button 30s" got
me a nearly clean access to the liveCD (minus reloading some Mate apps like
"show desktop").
Plus SeaBIOS chainloading GRUB was displayed on the external GPU!
But (the one and only but) launching the install starts for a bit, the the
screen freezes. I reboot, and back to SeaBIOS/GRUB not being displayed, and
no access to the LiveCD (like showing the desktop).
Trying again with that 30s trick, still the same display :_(
Any idea why? It seems unreliable/unstable.
But I'm on to something.
Also, it seems there's no kernel panic for now.
Maybe it has to do with this text-mode. I'm using a standard Debian LiveCD.
