Activate Maintenance Mode on my Galaxy One UI 5

Maintenance Mode protects your privacy while someone else is using your phone, such as when you're sending it for repairs. Follow the below steps for more info on enabling and disabling Maintenance Mode.

In Maintenance Mode, your personal data, including pictures, messages, and accounts can't be accessed and only preinstalled apps can be used. You'll need to unlock your phone and turn off Maintenance Mode. When you do, everything will go back to the way it was when Maintenance Mode was first turned on. Changes made while Maintenance Mode is on, such as downloaded data or settings changes aren't saved.