Booting custom Ubuntu fail

Hi there!
My name is David. I, along with the rest of the Kaldersvell team are trying to make our own distro named Kaldersvell, and we are having it based off of Ubuntu GNOME. This is a project that we, as high schoolers, are trying to attempt to do, so please bear with us. We do, however, all have quite a bit of experience in c++. And so, after applying only slight modifications, namely just changing backgrounds (in order to get a feel for the process). All names of the files that were altered stayed the same. We used squashfs in order to unpack. Then we resquahed. The OS was then burned onto a disk. After starting the computer from the disk, it begins to boot, and the boot screen even shows up. However, after a while we get the error message: "(initramfs) unable to find a medium containing a live file system." Does anyone have any ideas as to how to solve this issue? We have already tried switching to ACHI. It's a disk, so no worry about USB2/3. In bios other/legacy selected. All to no avail. Any help is greatly appreciated.
Regards,
The Kaldersvell team