Here are some steps to try in order to resolve the laptop not turning off when in tablet mode:

1. Check to ensure that the 'Settings/System/Display/Rotation lock' option is not enabled
2. Turn off automatic rotation in the settings.
3. Make sure the 'Allow the screen to auto-rotate' option is enabled in the control panel
4. Restart your computer and check if the display turns off in tablet mode.
5. If the screen remains on, try disabling the tablet mode in the settings.
6. Update your graphics driver and try again.
7. If the issue remains, contact customer support for additional assistance.