MacBook won't start up
Apologies for the long message, I'm really struggling to sort out my MacBook and any help would be greatly appreciated.
The other day my MacBook suddenly slowed right down and when I switched it on again later, it started to load and then switched off again. This is as far as it will go now.
I'm really not tech savvy and have looked all over for help and tried a few different things without success.
I can get into recovery mode and have tried to Reinstall Mac OS but get a message saying:
The operation could't be completed.
Permission denied.
Why is that and is it possible to fix?
I have looked into making a bootable installer but have struggled to even be able to download HighSierra at all let alone it being an app in the Applications folder to then turn into the bootable installer.
I have done First Aid but when I get to Macintosh HD it fails, getting stuck at Checking catalog file before failing. When I check the details it says :
The volume Macintosh HD could not be verified completely.
File system check exit code 8.
Restoring the original state found as unmounted.
Problem -69842 occurred while restoring the original mount state.
File system verify or repair failed. :(-69845)
Operation failed...
What do these problems mean and can I fix them?
I have no back ups of most of the stuff on my MacBook and have seen that you can transfer files between Macs using target disk mode. I'm borrowing someone else's Mac to try resolve my ones issues and I don't want to muck up theirs as well.
If my MacBook's meltdown is due to a virus, will this get transferred to the other laptop as well when I transfer everything else?
Thanks in advance for any advise in fixing this.
MacBook Pro