mbevks that prompt basically says something went wrong, and gives you a console/terminal to figure out what and fix it. To see details of whats broken you can run journalctl.
To copy the output of journalctl into a file do the following:
$ journalctl >> system_log.txt
Next check which drives are available on your system:
$ ls /dev/sd*
Example output:
/dev/sda /dev/sda1 /dev/sda2
Now insert your USB and rerun the above command:
$ ls /dev/sd*
/dev/sda /dev/sda1 /dev/sda2 /dev/sdb /dev/sdb1
You should see a additional (new) dive available, (I'll assume its sdb change the command below if its something else)
Next we mount your USB to /mnt:
$ mount /dev/sdb1 /mnt
Next we copy the data to your USB:
$ cp /run/initramfs/rdsosreport.txt /mnt/
$ cp system_log.txt /mnt/
Were done, you can shutdown now:
$ shutdown
If that doesn't work:
$ halt
Two possible reasons for not being able to boot:
- You ran out of disc space, In which case your computer will slow down to a near frozen state in which it will take a lot of time to run any command. Most OS's need some free space for your computer will not be able to successfully boot.
- The file-system got "corrupted", the EXT4 filesystem is "not safe" to suddenly power down. If it looses power during a write it can lead to incomplete/corrupted data being on your drive. This doesn't mean that it is unrecoverable, but you may have lost any data that was being written to.
If the OS recognizes corrupted filesystem that is still readable (and sometimes even a failing/dying harddrive), the OS will boot said drive in "read only" mode to protect the drive/filesystem to prevent additional/unrecoverable data loss. In which the OS will not be able to boot, since it isn't able to write to the disk.
These are the two worst case scenarios that have happened to me personally; the first requires you to be comfortable in navigating your filesystem and moving/deleting data using a terminal, the second is a loss of data that you can potentially do nothing about unless you have a backup.
That said, it could be something else entirely. With additional information we can see what actually went wrong, and what steps need to be taken to fix it.
