To fix this issue, all you need to do is to:
- boot with
nomodeset(or ssh into the machine) - enable the non-free repository, by editing
/etc/apt/sources.listand addingcontrib non-freeafter themainthat’s on some of the lines there already - run apt-get update
- install the
firmware-amd-graphicspackage, which will now be pulled fromnon-free. - reboot, this time without the
nomodeset, to activate the firmware.