I recently installed Debian 10 and liquorix(latest kernel) when I booted a blank screen apeared.
Swithing back to the old kernel worked, but the resolution of my monitor was poor. I tried to see what is the issue and ran :
dmesg
In that output I noticed this line:
drm:amdgpu_pci_probe [amdgpu]] *ERROR* amdgpu requires firmware installed
I searched on google a fix and got to this post.
The fix was simple, I added contrib non-free after main on every line from /etc/apt/sources.list. Then I ran:
apt-get update && apt-get upgrade
And then I installed firmware-linux:
apt-get install firmware-linux
And then I rebooted the PC.