So Henkaku has an automatic update blocker built in. So if you install henkaku your device shouldn't update. The other way is if you go into settings. You will go almost all the way to the bottom, there should be an option there that when clicked will take you to a screen that will show you options for automatic updates. Uncheck that option. You should do both of these by the way. The other update blocker is if you have ps plus. In settings you log into psn, and you can check membership options which should show you have the ability to toggle off an on for automatic updates.