MacOS – Boot to Single User Mode with Startup Manager

Issue solved; no physical errors. These are what I did:

First I analyzed where the error occurred :

...
** Checking catalog file.
Invalid index key
(4, 20220)
Invalid node structure
(4, 38065)
The volume SSD could not be verified completely.
...

fsck stops while scanning catalog files. Let's try reading fsck_hfs user manual by executing man fsck_hfs for clues.

...
-R flags Rebuilds the requested btree.  The following flags are supported:
     a       Attribute btree
     c       Catalog btree
     e       Extents overflow btree
...

Let's try rebuilding catalog btree then. fsck_hfs -Rc /dev/rdisk0s2

Results: fsck does not stop at catalog file check anymore, and the Invalid index key error disappeared, revealing more errors ( clues! ).

** Checking extents overflow file.
Incorrect block count for file Cache.db-wal
(It should be 114 instead of 119)
** Checking catalog file.
Missing thread record (id = 30291961)
Incorrect number of thread records
Incorrect number of thread records
** Checking multi-linked files
** Checking catalog hierarchy.
Invalid directory item count
(It should be 221 instead of 244)
Invalid volume file count
(It should be 1318081 instead of 1318117)
** Checking extended attributes file.
Invalid node structure
The volume SSD could not be verified completely.

fsck now stops when checking extended attributes file. Let's try rebuilding the attributes btree with fsck -Ra /dev/rdisk0s2.

Result(s): All errors, except Invalid node structure disappeared after the first repair attempt. It shows several invalid nodes, then attempts the second repair, and rechecks. It still shows some invalid nodes, but even less then before.

However the fsck stops with a message saying that it stops making repair attempts after 3 check failures. I ran fsck -Ra /dev/rdisk0s2 again. It attempts to repair again, then rechecks. No invalid node structure error shows up!

It now makes Invalid volume free blocks count, Invalid volume file count, and Invalid volume directory count errors, but it doesn't stop yet!

After yet another attempt of repair, fsck finished without any errors.

Shut down. Boot normally without entering single user mode. And it works! Problem solved by running fsck several times, rebuilding catalog btree, and attribute btree several times.

Give this a try. If you can get to single user mode you can remove the file that OS X checks for during boot to determine if the Mac has already been setup. If it doesn't find the file then it boots to the setup assistant, which allows you to create a new admin user.

Try resetting PRAM:

1. Shutdown the Mac
2. While holding ⌘+option+P+R, power on the Mac
3. Continue holding all four keys until the Mac has chimed (restarted) twice, then release the keys and allow it to boot normally

If that fails, or you still can't boot to single user mode, give this a try. Resetting NVRAM:

1. While holding ⌘+option+O+F, power on your Mac, after a few seconds you should be greeted with the Open Firmware screen.
2. Type and click return: reset-nvram
3. Type and click return: `reset-all'

Hopefully by now you can boot to single user mode.

1. Boot to single user mode (⌘+S while powering on)
2. Type and hit return: /sbin/fsck -fy
3. Type and hit return: /sbin/mount -uw /
4. Type and hit return: rm /var/db/.AppleSetupDone
5. Type and hit return: reboot

This should boot your Mac to the setup assistant. From here you can create a new user account, which will automatically be designated as an administrator account.

Hope that helps.