2014 MBP Will not boot, unable to repair disk, no backup

[ccy333]

I have two older Macbook pros.
#1 is Mid 2010 MBP with (1) Firewire 800 port and (2) USB 2.0 Ports, 500GB SATA Disk, running OS X Yosemite 10.10.5
#2 is 2014 MBP with (2) Thunderbolt "2" ports and (2) USB 3.0 Ports running OS X Yosemite 10.10.3

#2 MPB ran out of room on HD and battery died, when I next attempted to reboot, it would not turn on past opening apple screen. I have since done all that i can find to do to try and restore. Before I completely wiped out all info on disk, I wanted to check and make sure I had no other options. It was not recently backed up so I am attempting to do all I can in safe/recovery mode to try and save data.

I booted into recovery mode and attempted all solutions that I could find on the internet for Disk Utility , First Aid, Restore, etc.,.,
When using Disk Utility, First Aid, "Repair Disk Permissions" is not available to select.
When doing Verify Disk I am told "the volume XXX-xXX appears to be ok" in green lettering.
As it continues it show "invalid record count , Macintosh HD could not be verified completely" in red letters.
It then says that File System check exit code is 8
Error: This disk needs Repaired. Click Repair Disk.

Repair disk is still not an option to select.

The only thing that I was able to accomplish was to create a 840GB .dmg file of #2MBP saved on an external hard drive. I am uncertain if this will 100% be able to restore my MBP after reinstalling OS.

My questions:

1) Will i be able to use the .dmg file from #2 MPB to restore after reinstalling OS?
2) If not, is it possible to use MBP #1 in target disk mode? I can not find a senario of sending data from Thunderbolt 2 -->adapter--->Firewire800 being successful in target mode. I did not want to spend ~$100 on cable and adapter if not helpful.
3) Does anyone have any other options that may be helpful to try?

 

[Cory Cooper]

Hello and welcome.

Sorry for the delayed response.

At first thought, if the 2014 MBP was critically low on space and the battery cut out, it sounds like it may have corrupted the storage drive because you are getting the invalid record count error.

1) Sometimes you can use Disk Utility to restore a DMG file to a drive, but it will erase the destination drive and you don't need to install macOS first. But, if there is corruption in the OS on the DMG, it may not restore correctly or allow you to startup after the restoration.
2) You may be able to use an Apple Thunderbolt to FireWire Adapter adapter to connect the two in Target Disk Mode, but I can't guarantee that will work.
3) Since you have the DMG on an external drive, have you tried mounting the disk image to see if it is accessible?

Other options would be to verify the integrity of the DMG. If it mounts and you can access your files, you may be able to simply wipe the drive, install OS X, then manually copy your files back. Or, sometimes Alsoft DiskWarrior can repair the invalid record count error, as long as it isn't too bad and the storage drive isn't in hardware failure.

C