When you run the fsck command, are you certain you are running on the correct partition?
You can use lsblk or df -h to ensure that you find the partition.
In my case, it shows:
Filesystem Size Used Avail Use% Mounted on
udev
tmpfs
/dev/sda4...
Unmount the partition, first. On mine, it would be sudo umount /dev/sda4 - be sure to change the sda to what yours actually is.
Run fsck -vf /dev/sd-- (For mine would be /dev/sda4)
Or you can run fsck -y /dev/sd-- to make it repair without prompts as it runs.
You can use fsck -AR to run fsck on ALL filesystems (the R skips root since you cannot unmount it).
I need to be away from the computer for a while on this end.
If you can get the LiveUSB to work, you may be able to just do a Fresh OS Install and resolve the issue that way.