If your system hangs with LED code 555, it will most likely mean that one of your rootvg file systems is corrupt. The following link will provide information on how to resolve it:
http://www-304.ibm.com/support/docview.wss?uid=isg3T1000217
After completing the procedure, the system may still hang with LED code 555. If that happens, boot the system from media and enter service mode again, and access the volume group. Then check what the boot disk is according to:
# lslv -m hd5
Then also check your bootlist:
# bootlist -m normal -o
If these 2 don't match, set the boot list to the correct disk, as indicated by the lslv command above. For example, to set it to hdisk1, run:
# bootlist -m normal hdisk1
And then, make sure you can run the bosboot commands:
# bosboot -ad /dev/hdisk1
# bosboot -ad /dev/ipldevice
Note: exchange hdisk1 in the example above with the disk that was indicated by the lslv command.
If the bosboot on the ipldevice fails, you have 2 options: Recover the system from a mksysb image, or recreate hd5. First, create a copy of your ODM:
# mount /dev/hd4 /mnt
# mount /dev/hd2 /mnt/usr
# mkdir /mnt/etc/objrepos/bak
# cp /mnt/etc/objrepos/Cu* /mnt/etc/objrepos/bak
# cp /etc/objrepos/Cu* /mnt/etc/objrepos
# umount /dev/hd2
# umount /dev/hd4
# exit
Then, recreate hd5, for example, for hdisk1:
# rmlv hd5
# cd /dev
# rm ipldevice
# rm ipl_blv
# mklv -y hd5 -t boot -ae rootvg 1 hdisk1
# ln /dev/rhd5 /dev/ipl_blv
# ln /dev/rhdisk1 /dev/ipldevice
# bosboot -ad /dev/hdisk1
If things still won't boot at this time, the only option you have left is to recover the system from a mksysb image.
