After clicking through for a bit, you will see a page asking you to select a drive. Unless you created a “time machine” backup, you’ll want to pick the reinstall Mac OS X option. Now go back into the main repair menu by closing the disk utility. First thing you need to do is to select disk utility, select your Macbook’s hard drive and hit erase – this may seem redundant but I’ll explain in a moment. Eventually you will see the Macbook’s recovery tools. Now that the wifi is connected, you need to wait. If you had been able to connect without the boot menu, you should be already be in internet recovery and do not need to press anything. Once you’re connected, you want to hit “cmd + R” from that boot screen. Unfortunately if you’re at UMass, eduroam (or UMASS) won’t work, however you can easily connect to any typical home Wi-Fi or a mobile hotspot (although you should make sure you have unlimited data first). Eventually you will see a screen where you can pick a Wi-Fi network. To get there, power the computer on, hit the power button and very soon after, hold the option key. Luckily there is another way to connect, via apple’s boot menu.

If instead your MacBook lets you select a Wi-Fi network during this process, you’re in the clear and can skip the next paragraph. This tends to be because the Mac assumes it is already connected to Wi-Fi (when its not) and gives an error after it fails to connect to apple servers. There is a bit of a catch: if you do this straight away, there is a good chance that the Mac will get stuck here and throw up an error – error -3001F in my personal experience.

The way forward is to use the built-in “internet recovery” which, on startup, can be triggered via pressing “cmd + R”. It may seem like you just bricked your MacBook, but luckily there is a remedy. If you’re anything like me, you will (or already have) accidentally wiped your Macbook’s ssd.

Hard dsk maintenance for mac