Galaxy Note 9: What to do if the device is freezing and does not respond to the touch screen?
If after restarting the device you still find your device freezes sometimes or is sometimes unresponsive, there are some actions you can try to help correct this symptom:
1. Use the Galaxy Note9 Device maintenance menu to help optimize the device and check for “Malware” . (SMART Manager may not be available depending on the region or service provider)
2. Create Memory Space.
3. Check for software updates for your device.
4. Check your device in "Safe Mode".
5. Perform a factory data reset of the device. Before performing the factory data reset, remember to make a backup copies of all important data stored in the device.
If the problem is still not resolved, contact a Samsung Service Centre.