Lets start there.
Do you have any other kernels installed?
mhwd-kernel -li
If not try to install one:
sudo mhwd-kernel -i linux515
When booting you should have the option to select kernel at grub.
If you do not see grub attempt hitting Esc to show it.
You can query your currently running kernel to be sure:
uname -a
Once you are in a supported kernel you will want to remove the old one:
sudo mhwd-kernel -r linux59
From there we should attempt full upgrade:
sudo pacman -Syu
Then please also see this post for sharing system info (post your inxi):