Make a backup
Making a backup is an important part of preparing your Mac for service. Time Machine makes it simple to back up and restore all of your files, and other backup methods are also available. Learn how to back up your Mac.
Gather your information
If you still have your sales receipt, bring it with you to the service location. You might also need your Apple ID password and a form of personal identification, such as a driver’s license, passport, or other government-issued ID.
You should know the name and password of your macOS user account, in case you need to log in to your Mac at the service location. And if you're also using a firmware password, please turn it off before you get service.
Gather your products
Bring your Mac, power cable, and any accessories that you need help with.
If you arranged for mail-in service, just follow the packaging and mailing instructions you received.