Trouble Reinstalling macOS Sierra My dad was running macOS &amp; Windows on his Early 2015 MacBook Air, and both crashed. Apple’s service center said the only option was to reinstall macOS.

Using the Windows Command Prompt I backed up as much data as I could. Then I tried to reinstall Sierra, but couldn’t boot into the Recovery Partition. Internet Recovery never worked (at best it progressed to 10% then stopped).

So I deleted all my partitions and downloaded a Sierra image from someone who put it in Google Drive. I don’t know what I did wrong but it turned my hard drive into an “OS X Base System.”



I tried resetting SMC, PVRAM/NVRAM… Nothing worked.

Now when I start the Mac normally it tries to resume the macOS installation, but fails because the HDD contains an “OS Installation Media.”

Then I got my hands on a friend’s Mac that I used to Create a bootable installer for macOS. I now have the USB boot drive, but I cannot boot to it (it shows the Apple logo and then “No Entry”). Trying to boot to the regular HDD also shows “No Entry.”

I would appreciate any help reinstalling my Mac cleanly.
Here's a guide to get you going again.

Not sure if your question needs to be closed as too broad / too much 20 questions - technical support, but following Apple's erase and install process should fix this at the cost of any data you still have on that drive.

Can&#39;t start Mac in recovery mode - only get folder with question mark instead