Welcome to the forum!
Please see the following and post your system info as outlined here:
What packages? What “code”? Without knowing exactly what you did, it’s hard to help.
The Radeon R9 280 is a GCN 1.0 card and is only officially supported by the radeon
driver which does not support Vulkan.
However, you may be able to enable experimental amdgpu
support by installing the amdgpu-experimental
package. If that does not work and your system fails to boot, you’ll need to switch to a TTY and remove that package.