I have Samsung Galaxy S20 Ultra. it started several months ago and I don't know why.
It doesn't look like a full restart. I just see white screen and then lock screen again. Normally if I restart it, I see samsung logo/provider logo/knox secure logo.
-Phone has done it even on charge.
I have read about trying to figure out which app might trigger it, but the phone does not look like it is restarting....the time is literally 5s.
Please ensure your phone's software and apps in the Playstore and Galaxy Store are updated @Kr1ska7a
Assuming you don't have the Auto Restart turned On I would first try Safe Mode to see if the issue stops when in that mode.
If it does then an app or theme you've downloaded is causing issues.
It's then a process of coming out of Safe Mode and then deleting your downloaded apps one at a time until it stops.
If it continues in Safe Mode then clear the phone's system cache files partition.
And you can run a diagnostic test via your Samsung Members app under the GetHelp section.
If that does not help then the next step coukd be a factory reset.
> https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to hook up to a Computer or insert your earphones to enter into recovery mode.
> https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ will help to highlight if an app or theme etc is potentially causing issues.
Finally a Samsung Service Centre can check out the phone.
Daily Driver > Samsung Galaxy s²² Ultra 256Gb in Phantom Black.
The advice I offer is my own and does not represent Samsung’s position.
I have no affiliation with Samsung.