Press the power button then press and hold “Option” button until a menu of boot options appear on the screen.
Select the pen drive you have plugged into the MacBook
Select ‘Reinstall MacOS’, the type of MacOS to reinstall will change based on the MacOS you have installed aready. Once selected click, ‘Continue’
On screen will be the name of the MacOS you are about to install, click ‘Continue’ to begin
If you agree to the terms and conditions, click ‘Agree’ to proceed. You will be prompted again
You will be presented with a choice of storage media, choose which you would like to install MacOS to
Installing MacOS can take some time, it is recommended you plug the device in and set it aside
Part way through instillation the device will restart, this is normal and part of the install procedure
When presented with the screen to select your region the install procedure is completed
