Hi Adrian, Thanks for the fast reply. The firmware-amd-graphics was already installed (via linux-firmware-nonfree? I didn't install it manually). Still a black screen.
Or does this mean that /boot/grub is mounted read-only and I have to follow the procedure you described? Peter pvz@ibook:~$ sudo apt install firmware-amd-graphics [sudo] password for pvz: Reading package lists... Done Building dependency tree... Done Reading state information... Done firmware-amd-graphics is already the newest version (20210818-1). firmware-amd-graphics set to manually installed. 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
