readonly file system error need manual fsck
reboot VM in recovery mode.
check the partition name using fdisk -l command
check the main partition which is most of the time is first partition with name Disk /dev/xvda1 .
Check the size to verify and confirm it is the correct one.
run fsck on it using e2fsck -fy -C0 /dev/xvda1
now logout from ssh/console session and reboot vm (not recovery mode).