S21 RESTARTING

[Christman]

I believe that Samsung company cannot fix any type of their own phones after reading many posts, and my S21 started restarting after 3 months of the date I bought it, I contacted customer service many times and sent it 2 times to their service centre, what they can do is just a factory reset and update, and only that, and the phone started restarting again and again after few days... shame on you Samsung, you suppose to refund or change the phone because you already know from where did I bought it, I paid more than 1200 aud for this worst phone to have, and your service centre is the worst, I was loyal to your company at least for 12 years but from now and on I will change to apple which many of friends recommended, it is time to change  not just for me but for the whole family.

Note: how can you sleep well when you sell phone like a nightmare to the other people

[GoanGeek]

May be you have a rogue app.

[Glenntech]

As @GoanGeek has mentioned.
Could be an App causing the issue or a third party Theme.
It's quite possible by factory resetting the phone, it removes the problem and why it works ok for the repair centre.
Maybe try booting up your phone in safe mode and seeing if it still restarts.
If not its highly likely to be an app or Theme you have downloaded.
This sounds like it could be something like this as it starts after a few days as you say.

Make sure all the Apps and Themes are from a reputable app store like Google Playstore or Galaxy Store
Downloading from Unknown sources can be a risky thing to do

[JAMES4578]

Hi @Christman  There is the possibility there is a problem with a 3rd part app if you have these installed. therefore an idea to enter safe Mode as @Glenntech  confirm, tap Safe mode.  For anyone with issues it advisable to firstly  wipe the cache partition  after updates.

1. Turn off the device.
2. Connect To Computer or plug in USB-C Headphones , Press and hold the Volume Up key and then press and hold the Power key (plus Bixby Key if phone has one)
3. When the Android logo displays, release all three keys.
4. An 'Installing system update' message will show for 30 - 60 seconds before the Android system recovery menu options appear.
5. Press the Volume down key several times to highlight wipe cache partition.
6. Press Power key to select.
7. Press the Volume down key to highlight yes, them and press the Power key to select.
8. When the wipe cache partition is complete, Reboot system now is highlighted.
9. Press the Power key to restart the device.

Whilst there are are customers who have this issue and I am not minimising it many others are satisfied with their S21 devices.   Whilst I had iphones some time ago would  be unlikely to go back to them now and they offer little in the way of customisation.

[Christman]

All my apps are from app store, once after a factory reset in the same day without installing any app it restated twice, and why this all happenned after android 12??

[Christman]

I don't think so, because sometimes it restarts even if I made a factory reset and just keeping it with its original apps just for checking if an app is a rogue app.

[Christman]

I did exactly ad you mentioned then it start restarting continously !!! 

[Christman]

Another thing a minute ago it is restarted while in SAFE MODE, so now anyone can tell what is the problem with this phone??

Note: I didn't install any app in it.

[AndrewL]

@Christman: I'm sorry to hear that you're experiencing persistent restarts on your Galaxy S21. If the problem occurred in Safe Mode then, to troubleshoot the issue, please try heading to Settings > Battery and device care > Tap the 3 dots in the top right > Automation > Auto restart at set times, and toggle this option off. If this isn't applicable, go back to Battery and device care > Device protection > Scan phone, to check for any malware or suspicious activity. Let me know how you get on. 

[A_Google_user]

I had this issue. You can't fix it, its a hardware fault with a dodgy chip in the handset. There's a thread on my profile if u want to read it. I tried everything, even talking to samsung direct.. they wouldn't admit there was a problem even though their forums are full of the same complaints!!