fsck died with status code 4

Try the -y option.

From fsck manual:

-y For some filesystem-specific checkers, the -y option will cause the fs-specific fsck to always attempt to fix any detected filesystem corruption automatically. Some- times an expert may be able to do better driving the fsck manually. Note that not all filesystem-specific checkers implement this option. In particular fsck.minix(8) and fsck.cramfs(8) does not support the -y option as of this writing.

Sometimes fsck shows that a filesystem has no errors, but in reality it has. I had a similar issue once, and if you want to check that filesystem, you have to use force. I'm not sure what type of a filesystem you're using, but let's assume it's ext4:

Emergency help:
 -p                   Automatic repair (no questions)
 -n                   Make no changes to the filesystem
 -y                   Assume "yes" to all questions
 -c                   Check for bad blocks and add them to the badblock list
 -f                   Force checking even if filesystem is marked clean
 -v                   Be verbose
 -b superblock        Use alternative superblock
 -B blocksize         Force blocksize when looking for superblock
 -j external_journal  Set location of the external journal
 -l bad_blocks_file   Add to badblocks list
 -L bad_blocks_file   Set badblocks list

So, the line you need is:

# fsck.ext4 -pvf /dev/sda1