How do I install macOS Sierra on a blank hard drive?

[BenchFox]

I've recently got my hands on a unibody iMac from 2010. It already had Sierra installed on it, but the hard drive was partitioned frankly stupidly. The hard drive had a capacity of 1TB, but only about 17GB was usable as the boot partition. That partition couldn't be edited in any useful way, so I tried to format it using the command prompt on a Windows 10 install disk on my desktop.

I'd tried to make a bootable USB of Sierra using TransMac (I don't have another Mac computer) but I can't see it on the startup options menu. I also can't see my hard drive (it's entirely possible it didn't format as exFAT).

How do I get macOS installed with a USB on a blank hard drive?

 

[DarkPremiumCho]

Do you mean you want to make a macOS USB installer, and use that to install macOS to the 1TB drive in your iMac, and you don't have other working Macs right now? Try gibMacOS or just boot to Internet recovery mode on the iMac.

 

[BenchFox]

Yes, I want to make a bootable USB. I do have an eMac, but I don't dare try to get the hard drive in there, and I don't have any other Mac. Since I completely formatted the drive, I don't think I have Internet recovery mode.

How do I make a recovery USB on Windows with gibMacOS?

 

[DarkPremiumCho]

The Internet recovery function resides in the firmware. It does not require a working Macintosh HD. Try this guide first.

 

[BenchFox]

I'll try it again this evening, but I'm near-certain it didn't work the last time I tried it.

Will update you on my progress.

 

[BenchFox]

Yep, I tried both the Magic Keyboard and a standard wired keyboard. I still just get a blinking folder icon.

 

[BenchFox]

How does gibMacOS work on Windows?

 

[DarkPremiumCho]

I still just get a blinking folder icon.

Looks like the previous owner did not update the firmware then.

How does gibMacOS work on Windows?

It's hosted on GitHub. They don't seem to be have an official guide but I've found a blog post.

gibMacOS runs in a Terminal window with interactive menus. Be extra cautious if you are not familiar with command line.

 

[BenchFox]

It says underneath the blog post that I'm ready to configure my EFI folder. Is that something that concerns me here, or should I just stick the USB in the iMac and try to see if it works?

 

[BenchFox]

BIG UPDATE: THE BOOT USB WORKS!

I am now in macOS Utilities.

Unfortunately, we're still not out of the weeds. Despite it detecting the 1TB hard drive, it tells me that there's only 2GB of storage, of which about 800MB is usable. It won't allow me to install High Sierra (as long as the version is officially supported, I'm fine with it).

Is the hard drive a lost cause? Or is this a software issue?

 

[DarkPremiumCho]

Is that something that concerns me here

Usually no.

it tells me that there's only 2GB

Have you erased the hard drive? Post some screenshots. On the Menu - Utilities - Disk Utility - Menu - View - Show All Devices, select the hard drive and click Erase.

 

[BenchFox]

YES, IT WORKED! I just had to erase and now I have the full TB of space. I installed High Sierra, and it all works now!

Moral of the story: Instead of TransMac, use gibMacOS to make a bootable USB.

Thank you so much for your help!