smartrecovery wrote:
Not sure which version of Internet Recovery Mode I'm using, but I have already discovered that if I use Cmd+Alt+R, it gets a different (and better) result than just Cmd+R. With the former, I get as far as "the erase process has failed". With the latter, it doesn't even give the option (greyed out).
Sounds like you are likely booting the macOS 12.x Monterey installer with the former and macOS 10.11 El Capitan with the latter. This also means you have had at least macOS 10.12.4+ installed at some point in the past since you have Internet Recovery Mode available. You can identify the installer by the OS it wants to install on the main installer/recovery mode screen.
When using the Monterey installer, try to erase the whole physical SSD two times back to back if you encounter an error message the first time. Once in a while for whatever reason I have found this is necessary. And make sure to select the whole physical SSD to erase. Within Disk Utility you may need to click "View" and select "Show All Devices" before the physical SSD appears on the left pane of Disk Utility. Erase the whole physical SSD as GUID partition and APFS (top option). If even this fails, then it is possible the SSD may be bad.
If you are trying to erase the disk while booted to the El Capitan installer, then again, make sure to select the whole physical SSD to erase which should be the top most item on the left pane of Disk Utility. The physical drive should be identified by its make & model, perhaps something like "Apple SSD AP256....". With El Capitan you need to erase the whole physical SSD as GUID partition and MacOS Extended (Journaled).
If you have a spare external USB3 drive, then you can try installing macOS onto the external drive. If this works, then most likely the issue is restricted to the internal SSD. Plus having an external macOS boot drive with a full OS also allows you to run a third party app DriveDx to check the health of the internal SSD even though Apple SSD's have very little health information these days, but you never know it may reveal a problem. Booting macOS from an external drive may allow you to continue using the laptop until the issue is sorted out. It is also possible to check the health of the SSD by booting from a bootable Linux USB stick.
Why were you trying to reinstall macOS? What issues were you having with this laptop before attempting to reinstall macOS? That issue may also be why you are having issues reinstalling macOS.
Try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the diagnostics rarely detect hardware issues.
I'm really confused as other forums/threads seem to suggest you don't 'need' to erase the disk, but officially Apple from what I gather states you have to do that before anything else? Or am I misunderstanding the Reinstallation process?
It depends on whether you want to perform a clean install or just reinstall macOS over top of itself. A clean install involves first erasing the drive which destroys all existing data on the drive. Reinstalling macOS over top of itself retains user data and most settings.
With macOS 11.x+ (perhaps even 10.15.x), reinstalling macOS over top of itself really won't do anything these days since the macOS system files are located on a signed & sealed read-only system volume, so there is no way these critical system files will be accidentally modified....so reinstalling macOS over top of itself really doesn't do anything these days.
The purpose of a clean install is usually for testing whether you have a hardware issue or a software issue, or as a way of removing junk that has built up over the years as long as the user does not restore from a backup since that just brings back all the clutter. Testing with a clean install of macOS without any third party apps installed and without restoring from a backup is the easiest way to confirm a hardware issue since only macOS is running on a clean install. If you are trying to convince Apple to repair your device, then being able to prove that the issue occurs with a clean install is the best way to do so since Apple cannot blame any third party apps or odd configuration issues. Unfortunately most users don't understand the purpose of a clean install is for testing the system this way...users tend to rush things by restoring from a backup because they just want to get their stuff back and use the computer normally so this usually ends up as a waste of time for most people.
The other time a clean install is necessary is when Disk Utility First Aid is unable to repair the file system, so a clean install will fix the file system issues because erasing the disk creates a fresh new file system without any issues.
