/dev/sda1 contains a file system with errors, check forced.
...
Inodes that were part of a corrupted orphan linked list found.
/dev/sda1: UNEXPECTED INCONSISTENCY: RUN fsck MANUALLY.
(i.e., without -a or -p options)
fsck exited with status code 4
The root filesystem on /dev/sda1 requires a manual fsck
BusyBox v1.27.2 (Ubuntu 1:1.27.2-2ubuntu3.3) built-in shell (ash)
Enter 'help' for a list of built-in commands.