So, I have run into a issue with my Galaxy S20 Ultra. Earlier tonight it began to lag alot, so I went to go reboot my phone. Upon rebooting it it took seven attempts to unlock the phone because every time I would try to swap up the screen either wouldn't respond or respond several seconds later then not unlock my phone. When trying to put my pin in it would lag so bad half the time I couldn't even properly put the correct numbers in.
When I did finally get pass the unlock screen the lag continued. Eventually a error popped up at the bottom of my screen saying; 'Processing System isn't responding.' It gave me the option to close out the app or whatever. So, that's exactly what I did. When I did this nothing really happened. Until, something did. A few minutes after hitting close app my phone shut itself off. And refused to boot back up.
It stayed like that for several minutes straight, even when plugging it into the charger hoping that it'd least force the screen on didn't do anything. Then, the screen would flash a few times. The phone would attempt to boot back up, then shut itself off again. Every time the phone's screen would flash it'd flash green for a brief moments. And every time the phone would shut itself off green lines would horizontally run across my phone's screen. This also occured when trying to boot it back up. Eventually though, it did boot back up. But nothing changed, still took several attempts to unlock my phone. The phone would then either lag really badly or straight up freeze. Then, shut itself off again.
So far, I haven't been able to put it into safe mode. Because everytime I try to my phone shuts itself off, then turns itself back on, then shuts itself off again. Im not sure whats causing this. But all I can say with certainty is that this issue all started due to it beginning to lag very badly. As of typing this out and posting it my phone has shut itself off, and hasn't come back on. Its been about 10 minutes since that has happened.
There is a hardware button press to force it to boot into safe mode. I'd start there. On my S24U it's pressing and holding volume up during boot. Idk what it is for your phone but it definitely has a way to do the same. Start there id say. Any idea what your internal storage situation is? Are you closer to maxing it out or do you have plenty of ufs storage left? The crashing sounds like your system is crashing. If this persists, force it into recovery and try clearing the cache partition. If that still doesn't work, a factory reset is likely in the near future for you. It's sounding like something is eating all your resources and the system isn't able to reclaim any of it causing the partition fail. There are very simple and easy FsTrim apps that require no root , only adb shell access using Shizuku or a computer if you have one. Good luck
