Unlock phone issue

[1bellb]

I have a Samsung Galaxy Note 9, and sometimes (few times per week) when I unlock my phone (using fingerprint) the homescreen shows for a split second, then goes totally black so I can't see anything. If I then lock and unlock the phone, everything show just fine without any issues.

Does anyone know why it sometimes shows the black screen after unlocking?

 

[mustang7757]

Hi, is the phone completely stock , no 3rd party lock screens or Samsung good lock app?

 

[mustang7757]

[Moved this to Note 9 forums]

 

[1bellb]

Yeah, its completly stock.
The only settings I have that aren't really standard is the always on displayed turned on, and I have contact information set to show on the lock screen. Thats it.

 

[VidJunky]

How predictably is this happening? I know you say it has happened few times a week but if you cycle the device between sleep and wake several times will it happen or only after it's been sleep for awhile or it doesn't matter if it was just on and you wake it again it might happen and you just never know?

Ask because one way to rule out this being caused by an app would be to run the device in Safe Mode but if it takes days to happen... No one wants to be in SM for days.

Is there anything you can say about this. Any pattern you've noticed? It only happens in the morning when you first check the device. It seems to happen more if I played this game or used this app before putting the device on the charger. It happens more if I have the device charging than when I'm out running on battery all day.

If it is that unpredictable I would try this, try closing all of your background apps before putting the device to sleep. Bring up the multi-task screen and close all open apps for two days or so and see if it happens. It's a lot of work and remembering but if it is being caused by an app this might help narrow it down.

From your description you are putting the device to sleep then waking it. So you're pressing the power button twice when this happens? Once to seemingly put the device to sleep and once to wake it again? If it goes dark and you attempt to make a selection on the screen can you open an app? This leans more towards a hardware issue. I might put an app on the home screen, something like a game or a messaging app, in a spot I know I can find even with the screen dim. When you attempt to wake the device and it does this try to open that app. Then check to see if the screen comes on when the app is opened and/or see if the app is open when you wake the screen again and it's working. I'm not sure what to think if the screen lights if the app is opened... That will take some more thinking. However if the app is open when you unlock the second time that would begin to sound like a back light issue. From there I'd try to figure out if the screen is displaying anything, which without a backlight can be difficult. You might be able to shine a light on the screen from an angle or something to see if your icons are present. You could also try covering the light sensor at the top of the phone, holding it briefly, then releasing it. If you're using adaptive brightness, the screen normally dims in dark places to reduce eye strain and brightens in light places to make the screen glare resistant. In essence you would be nearly turning the backlight off and then on again.

Let us know what you find.

 

[mustang7757]

Yeah, its completly stock.
The only settings I have that aren't really standard is the always on displayed turned on, and I have contact information set to show on the lock screen. Thats it.

Did this happen after a update? What security patch its on and is this unlocked version or carrier?

 

[1bellb]

@VidJunky - From what I've noticed it seems completely unpredictable. It can happen if my phone has been sat on my desk for a while, it can happen when I unlock it after receiving a notification and it can happen when I lock the phone, then unlock it immediately. I did just try locking and unlocking 20+ times and I wasn't able to reproduce the issue.
I use my fingerprint to both unlock the device and to give me access. So there is no double pressing of the power button. The 2 apps that are generally always open is my Email (Samsung's default app), and the Amazon music app as I'm generally always listening to music. But I can confirm this has happened without the Amazon music app being open. I'm also not using the adaptive screen brightness, so that won't be the issue.
But I will try what you've suggested to close all apps, and also attempt to open an app on the black screen to see if its open when I lock and unlock again.


@mustang7757 - This issue has actually been happening for many months if not over a year. The security patch level is: 1 October 2020, and this is the unlocked version of the phone.

 

[1bellb]

Sorry for the late response on this.

So, I just unlocked my phone and the screen was black. I pressed on the screen where my phone app icon would be, locked the phone and unlocked it again and I can confirm that the phone app was open. So the screen is active, its just showing the black screen.

Not sure if this has anything to do with it. But it does tend to happen more often when my phone is faced down. I use the fingerprint scanner on the back of the phone to unlock it as I'm picking it up and turning it around.