System failure after attempted upgrade to High Sierra--now what?

[JoannaCW]

My mother has a 2017 MacBook Air which was running OS X Sierra (or High Sierra--sorry, not sure which.). Yesterday when her computer said upgrades to Sierra were available and asked if she wanted to update now, she clicked Yes and went off to do something else. When she returned she got a message whose exact wording she can't remember saying in effect that the operation could not be completed. She clicked OK and got a black screen with a flashing icon of a folder with a question mark on it.

My brother shut the computer down manually, restarted, got nothing; restarted again in Recovery mode; ran First Aid and was told the HD was fine. He attempted to reinstall the OS from Recovery mode and it didn't make any progress overnight.

This am we canceled the attempted download. My brother tried to erase the disk in Disk Utility and do a clean reinstall. OS X Base said it could not be erased--that it was impossible to unmount the system in which the computer had been started up. The hard disk, however, says it is erasable...we haven't tried that. We then went into the Apple menu to Startup Disk. No startup disk could be found. My brother has also tried resetting NV and PRAM; this didn't help.

I realize my mother's data is probably lost; that's OK as most of it was still stored on her old computer (this one is quite new.) But what can we do to get the computer back to functioning with a clean OS? DO we need to buy a disk to install from? Is there likely to be a hardware problem which a disk would not fix?

Sorry for the confusion. Any advice greatly appreciated.

 

[Shadow Jolteon]

It sounds like it may be some sort of hardware issue. One last thing you can try is running Apple Diagnostics, which would be by shutting the computer down, then immediately hold the D key until you see either a language selection, or a screen with a loading bar saying "Checking your Mac...". After it completes, it will let you know if any hardware problems were detected. Either way the diagnostics turn out, it would probably be easiest to take the computer to Apple or to an authorized repair center, since your machine is very likely still under warranty.

As for buying installation discs, Apple does not make discs for their operating systems any longer, and only distributes macOS upgrades via the App Store. Using tools included with that installer, you can create a bootable flash drive, though you would need access to another Mac and a spare flash drive you can wipe for this.

https://support.apple.com/en-us/HT202731 - Apple Diagnostics
https://support.apple.com/en-us/HT201372 - Making a bootable macOS installer.

 

[Fishrrman]

It's under warranty.
Take it to a brick-n-mortar Apple Store genius bar and ask for help.

If it was me, I'd put Low Sierra (NOT High Sierra) back onto it and "leave it there".
High Sierra seems to be "a bag of hurt" for too many folks right now.

Does she have stuff on there that needs to be backed up first?
Do it, or otherwise she'll lose it.

 

[Weaselboy]

My brother tried to erase the disk in Disk Utility and do a clean reinstall. OS X Base said it could not be erased-

It does sound like she may have had some sort of hardware failure coincidentally when the OS upgrade was being applied.

But you can try erase the drive and reinstall the OS if you want, but you are going about it wrong. It sounds like you are in command-r recovery and that is why the drive is locked. You need to boot while holding command-option-r to get to Internet recovery. That will allow you to erase the drive and hopefully reinstall the OS.

If there is important data on there she really needs, stop right now and get it somewhere where you can pay to have the data recovered. The more you try over and over to reinstall, the less likely you will be able to recover her data.