Alright got a couple questions for you. Let's check your lock settings, please unlock your phone, and go to the settings button so we can search for: "Lock screen" and select the first option.
1. Do you have smart lock enabled? (2nd item in list on my s8) It's the feature that keeps your phone unlocked by a certain location or nearby devices. Let's assume you have this off.
2. Tap into "Secure lock settings" (3rd item in list on my s8). I've got the following enabled:
- Lock the phone 5 seconds after the screen turns off automatically.
- "Lock instantly with power key" is enabled
-"Auto factory reset" is disabled
-"Lock network and security" is enabled
-"Show Lockdown option" is enabled
3. Now on the https://findmymobile.samsung.com/ website. When the lock button is pressed, fill in the info for the PIN and the other 2 steps. Phone will become locked with that PIN.
4. Unlock phone with that PIN. Press the lock button again to lock the phone. Turn on screen and while on the lock screen, press and hold the power button, tap on the power off button when it appears, and once more, and now it should prompt to enter a PIN or biometrics. And that should do it, a theif would not be able to power off your device at the lock screen.
5. Please note if you have facial recognition turned on or the fingerprint scanner on, do not have your finger on the scanner or your face in view of the camera, because the device will pick up that information right away and turn off and make it seem like the PIN was not required.
