If your phone won't turn off when you press the Power and Volume up buttons simutaniously, try the following:
1. Check if the button is faulty.
2. Check if your phone is in a state of crash, or is stuck. Press and hold the power button for over 12 seconds to force restarting your phone.
4. Uninstall and delete any recently downloaded software.
5. Back up any important data and restore your phone to factory settings.
If the issue persists, contact the Nothing Support Team for further assistance.