I had the same issues with M30s. My phone will suddenly freeze and then reboot. If I am playing a video, the audio will get struck until it reboots.
After a lot of tries, I think I know why it is doing it. The phone can't thermal throttle. CPU can run in his maximum speed for some time. Why? Because more speed means, more energy. All the energy/power is converted to heat. CPU has temperature limit above which it won't work. To solve this, kernel would freeze and restart the system. But before kernel taking this step, Operating System should slow down the CPU power. This is not happening.
Install Geekbench5 from Playstore. Try to run the test. It won't complete. For me, it got struck at 60% a lot.
I did 2 things to solve this:
- Turning power saving mode
- Downgrade my software update to android 10 (I understand this is tough but it can be done without rooting)
I have done both these steps. I have since tried to freeze my phone by running Geekbench5. It is been more than a day. I haven't faced the issue. MY Geekbench score is less than average. Which means my CPU is operating at a lower speed but that's good as it won't hit the temperature that causes the problem.
Let me explain how to do the 2 steps and why it might work
Turning power saving mode
Go to Settings -> Device Care -> Battery -> Power mode
Select Medium power saving One of the thing this does is reduce the CPU speed to 70%. It was turned off for some reason. If it is already on, try formatting the phone and turning on Medium power saving.
Downgrade to android 10
For a lot of people, this issue started when an update is done. It is the same for me. It is a good practice to install updates. However, Samsung doesn't seem to realise they screwed up with M30s and pushing a defective product or bad software.
This video explains how to install old firmware https://www.youtube.com/watch?v=xuV5-v91IUA Need a windows laptop to do this though
- Download the firmware from here: https://samfrew.com/model/SM-M307F/region/INS/ It will take time to download on the free version.
- Download odin from here: https://forum.xda-developers.com/attachments/odin3-v3-14-1_3b_patched-zip.5158507/
- Download samsung drivers: https://developer.samsung.com/mobile/file/4d05badf-eaea-4095-af16-3aabfad74760
- Unzip the firmware - it will have 5 files(Watch the video for more details).
- install samsung drivers
- Open odin software - Map 4 files as mentioned in the video
- You need to go to download mode to install the software. Switch off your phone. Press volume up+down. Connect usb cable from your system to phone. This should go to download mode. Press volume up to confirm.
- In the odin software, it should detect your phone. Start and it will install. Leave the phone and laptop undisturbed.
- The phone will restart and android 10 is installed.
- Once it is installed, you still need to turn Medium Power Saving Mode on. Installing previous firmware alone didn't solve the problem. Only with previous software + Power saving mode, it seems to have solved my issue.
I will update the post if it doesn't work out. Knowing the issue means I can take steps towards it. Don't run too many apps. It should be noted that this is a Samsung problem. Either software bug or manufacturing issue that is left to be solved by their customers.
Dear Samsung Member,
Greetings from Samsung Customer Support!
To resolve your device hanging issue please visit this link: https://www.samsung.com/in/support/mobile-devices/how-to-restart-the-device-when-freezed-or-hanged/
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
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Samsung Customer Support
Enabled power saving mode, downgraded from Android 11 to Android 10. My device still keeps restarting. It's 100% hardware issue! Automatic, random restart issues started occurring since updating to Android 11.