Suddenly my MacBook Pro 2017 running Sierra 10.12.6 crashed and couldn't pass the boot loop (stuck at the apple logo with the filled progress bar for hours)
Then I restarted with
command+R and tried to back up my main disk to an external HDD but it fails.
I got the following error:
Validating target... Validating soruce... Validating sizes... Restoring Could not restore - Device error Operation failed
I tried to reset NVRAM with holding down Option+Command+P+R, but did not help. When I run first aid from the Disk Utility, it says:
File system check exit code 8. Updating boot support partitions for the volume as required. File system verify or repair failed. Operation failed...
I run the hardware check (command+D on restart) and it couldn't find any issues. So it is a still matter of software problem..
Then I have created a bootable USB (ownership ignored on the usb) from Sierra 10.12.6. It boots from USB well but when I try to install Sierra on my Macintosh HD got the following message:
The operation couldn't be completed. Permission denied
Do you have any suggestions on how to install Sierra again and/or backup my disk?