Comment 42 for bug 1779827

How do you install test kernel?
I tried dpki -i linux-modules-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb linux-modules-extra-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb linux-image-unsigned-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb

but I get error:

Preparing to unpack linux-modules-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb ...
Unpacking linux-modules-4.15.0-24-generic (4.15.0-24.26+crng4) over (4.15.0-24.26+crng4) ...
Preparing to unpack linux-modules-extra-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb ...
Unpacking linux-modules-extra-4.15.0-24-generic (4.15.0-24.26+crng4) over (4.15.0-24.26+crng4) ...
dpkg: regarding linux-image-unsigned-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb containing linux-image-unsigned-4.15.0-24-generic:
 linux-image-unsigned-4.15.0-24-generic conflicts with linux-image-4.15.0-24-generic
  linux-image-4.15.0-24-generic (version 4.15.0-24.26) is present and installed.

dpkg: error processing archive linux-image-unsigned-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb (--install):
 conflicting packages - not installing linux-image-unsigned-4.15.0-24-generic
Setting up linux-modules-4.15.0-24-generic (4.15.0-24.26+crng4) ...
Setting up linux-modules-extra-4.15.0-24-generic (4.15.0-24.26+crng4) ...
Processing triggers for linux-image-4.15.0-24-generic (4.15.0-24.26) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.15.0-24-generic
/etc/kernel/postinst.d/zz-update-grub:
Generating grub configuration file ...
Warning: Setting GRUB_TIMEOUT to a non-zero value when GRUB_HIDDEN_TIMEOUT is set is no longer supported.
Found linux image: /boot/vmlinuz-4.15.0-24-generic
Found initrd image: /boot/initrd.img-4.15.0-24-generic
Found linux image: /boot/vmlinuz-4.15.0-23-generic
Found initrd image: /boot/initrd.img-4.15.0-23-generic
Found linux image: /boot/vmlinuz-4.15.0-22-generic
Found initrd image: /boot/initrd.img-4.15.0-22-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done
Errors were encountered while processing:
 linux-image-unsigned-4.15.0-24-generic_4.15.0-24.26+crng4_amd64.deb

Or how do I revert to previous working kernel (I don't have grub installed... long story).