this is the step that i done yesterday when my Centos fail to boot because of electricity problem. this is for checking file system concurrency when ask by the system.
please be sure to specify file system
fsck -t ext3 /dev/sda1 or
answer y for all question that came up, tryto use :
fsck -y /dev/sda1
once it has finished, remount file system : mount /usr/u02
read man fsck for further information.