Database Users

Beware of the Brightness Of Death

Hi all,
On a number of occasions, I've used Market apps to control the screen brightness, either manually (like a brightness widget) or scheduled (using Timeriffic - a great tool for automatic profile changes throughout the day).
Apparently, these apps are not aware of the correct minimum brightness supported by the Leo, making it too easy to go too low, which essentially disables the display completely.
Touch still works, so if I'm lucky enough to remember the location of the widget/slider/controls, I may be able to turn brightness back up to a "sane" level.
For example, Timeriffic turns the screen off with a brightness level of 10% - 15% is the lowest working setting.
If I'm unable to fix it this way, I'm basically forced to reset. The problem is that Android *remembers* this setting after a reboot, and reapplies it just when the device is vibrated slightly at the "Android" logo animation. Thus, with a black screen, it is impossible for me to unlock the SIM, hard to unlock the screen lock, and virtually impossible to correct the brightness setting. I need to remove my data.img ("hard resetting" Android) and restore what I can from backups.
The problem also seems to occur with the standard screen dimming which occurs at about half time before the "screen off" setting. I can see the display start to dim, then it suddeny turns off. In this case, however, Android of course reverts to normal brightness at the touch of the screen or press of a button.
On a related note, I have experienced (like right now) that brightness range used by Android is much dimmer then normal. That is, using the regular brightness slider in Settings, I can only vary between almost invisible (min) and quite dim (max). Curiously, in this situation, the display can get *much* dimmer than normal, without becoming disabled.
Any ideas on these issues would be most welcome!
Workarounds found later in this thread:
- Shine a bright light on the screen - the graphics are still there if you look really hard. It's not a joke!
- Use Screencast in Droid Explorer to "remote control" your Android
- adb shell "echo 255 >/sys/class/leds/lcd-backlight/brightness"

ugumba said:
Hi all,
On a number of occasions, I've used Market apps to control the screen brightness, either manually (like a brightness widget) or scheduled (using Timeriffic - a great tool for automatic profile changes throughout the day).
Apparently, these apps are not aware of the correct minimum brightness supported by the Leo, making it too easy to go too low, which essentially disables the display completely.
Touch still works, so if I'm lucky enough to remember the location of the widget/slider/controls, I may be able to turn brightness back up to a "sane" level.
For example, Timeriffic turns the screen off with a brightness level of 10% - 15% is the lowest working setting.
If I'm unable to fix it this way, I'm basically forced to reset. The problem is that Android *remembers* this setting after a reboot, and reapplies it just when the device is vibrated slightly at the "Android" logo animation. Thus, with a black screen, it is impossible for me to unlock the SIM, hard to unlock the screen lock, and virtually impossible to correct the brightness setting. I need to remove my data.img ("hard resetting" Android) and restore what I can from backups.
The problem also seems to occur with the standard screen dimming which occurs at about half time before the "screen off" setting. I can see the display start to dim, then it suddeny turns off. In this case, however, Android of course reverts to normal brightness at the touch of the screen or press of a button.
On a related note, I have experienced (like right now) that brightness range used by Android is much dimmer then normal. That is, using the regular brightness slider in Settings, I can only vary between almost invisible (min) and quite dim (max). Curiously, in this situation, the display can get *much* dimmer than normal, without becoming disabled.
Any ideas on these issues would be most welcome!
Click to expand...
Click to collapse
I don't know these app(s) but if they are writing their settings and configured values into a ini or settings file, than you might be able to connect via adb and change the setting by this way.
With tools like Droidexplorer or ADB magic, browsing through the files should be very comfortable and you might find the correct file.

this happens on regular android devices ...i have a couple of them

thatruth132 said:
this happens on regular android devices ...i have a couple of them
Click to expand...
Click to collapse
What happens? That brightness is set too low, essentially disabling the screen, so you're forced to hard reset or perform some root magic? How do you cope with it? Or does it happen that the permitted brightness range is just dimmer than usual?

Btw, until there is no light-sensor support in kernel, you can't use such apps for the brightness

Stills a good advice

I have had the same issue with the brightness range being too low. The max brightness is really dim and the colors don't seem right. That may just be the dimming effect though. If I restart the phone it seems to take care of this. I have not had the screen go below the minimum level and turn off though.

is there a fix for this. i just experienced this problem

I experienced the same with Multicon widgets.. had to delete Android and start over

somebully said:
I experienced the same with Multicon widgets.. had to delete Android and start over
Click to expand...
Click to collapse
Oh wow, not good at all, crap...
so that means if i do that i'll lose everything huh?
Theres no way to restore the factory brightness or factory settings for the android?

aznsHD2 said:
Oh wow, not good at all, crap...
so that means if i do that i'll lose everything huh?
Theres no way to restore the factory brightness or factory settings for the android?
Click to expand...
Click to collapse
As long as you have a working WinMo it should be possible to edit the values of brightness, but I have no idea where this information is stored.
Deleting Android folder and unzipping again is esentially restoring to factory settings.

yea this happens to me all the time, its a *****. it cuts off at exactly 12% for me. what i do is have aldiko(a book reader) on the home screen. if i click on it and open a book i can just swipe on the left side of the screen to adjust brightness. since i know that its on the home screeen on the right side middle, i can usually find my way back to it.

somebully said:
As long as you have a working WinMo it should be possible to edit the values of brightness, but I have no idea where this information is stored.
Deleting Android folder and unzipping again is esentially restoring to factory settings.
Click to expand...
Click to collapse
which means that i'll lose everything such as data correct? new contacts etc. msgs...

any thing on this... isnt their a file in the android folder that i could maybe replace to restore to factory settings.
and could someone post a screen shot of their phone so i know where the numbers for the pin code lockscreen. tryin to get past that, then i can adjust my brightness

LOL I experienced it one time. And I must delete data.img to restore the phone. After this, I don't use any brightness tools (except ones already in the Android build).
If anyone have solution, please point us

Well i was able to get my screen back to normal. lol.
I didnt delete the data.img, i simply copied it and then removed it, started a fresh install, and then just marked on my screen where the numbers were, turned it off, put the old data.img back. Followed my marks, and was able to unlock it and then found the power control widget. And bam! screen back to bright...

This might work for you!
Erm... In similar circumstances I found this worked...
I was trying out different Android builds and I found a screen brightness widget. It had various available levels of brightness, one being 0%. As soon as I selected it I felt pretty stupid as true to it's word it gave me 0% brightness placing me in a similar position to the OP.
My Solution. I used my (very bright) led torch to light the screen. By playing around with the angle and beam width I found I could just make out the on screen graphics enough to re-adjust the brightness level.
Simples!

Just as " Justblair " said .. you can place your device under a very bright light thus you'll be able to see the screen and what it's showing .. idk what build you guys are using but in cyanogen you can adjust the lowest dim level so that any app or widget tries to set the brightness to 0% it's automatically set to your preset, 15% for instance.
I've only faced this problem once

Is it absolutely necessary to flood the main thread with all these useless noob posts?
It really has nothing to do with Android development on HD2 and should be posted in the General section IMO.

kawazaki said:
Just as " Justblair " said .. you can place your device under a very bright light thus you'll be able to see the screen and what it's showing .. idk what build you guys are using but in cyanogen you can adjust the lowest dim level so that any app or widget tries to set the brightness to 0% it's automatically set to your preset, 15% for instance.
I've only faced this problem once
Click to expand...
Click to collapse
Cyanogen allows you a max dim level of 26 - which is too little on the HD2.
In Tasker, 30 is the lowest setting that still provides light. Maybe Cyanogen can be patched for the HD2 in coming builds?
Thanks for the tip on shining a bright light on the screen.
Another tip is to use Droid Explorer's "Screencast" feature, to view and control your Android's screen on your PC desktop. Of course, the brightness setting has no effect here.

Brightness adjustment fail

I installed a battery booster app from the market, and it had an option to dim the screen, it was on 11%, well i tried to adjust it, and i guess i went way to far and it turned my screen black, i cant see nothing.
im on the Darkstone build.
is there a way to either delete that app or what, i know the phone works as i feel the vibration from me sliding it to unlock from home screen.

aznsHD2 said:
I installed a battery booster app from the market, and it had an option to dim the screen, it was on 11%, well i tried to adjust it, and i guess i went way to far and it turned my screen black, i cant see nothing.
im on the Darkstone build.
is there a way to either delete that app or what, i know the phone works as i feel the vibration from me sliding it to unlock from home screen.
Click to expand...
Click to collapse
The LCD still light up but very dim, so try going into a dark room and wake up the phone. Then you will be able to see the contain on your phone.

10507 said:
The LCD still light up but very dim, so try going into a dark room and wake up the phone. Then you will be able to see the contain on your phone.
Click to expand...
Click to collapse
no its literally black, i cant see anything.

aznsHD2 said:
no its literally black, i cant see anything.
Click to expand...
Click to collapse
Not even in a totally dark room?

10507 said:
Not even in a totally dark room?
Click to expand...
Click to collapse
Like i said it is BLANK. seriously blank. its not dim or nothing.
Is there a way to restore the brightness on here, because i cant see anything im doin on it.

what you can try to do is, grab a friends phone and try to immitate the same touches on both devices, the best way to do it is by unlocking it, pressing the menu key, click on the corner to make sure u go to the settings, scroll all the way up and find your way to "display" tipically the 4th (or 5th in my case because i have cyanogen mod) and brightness (should be the one at the top) and just try to drag ur finger from left to right to increse it (as it should over pass any 3rd party app) and see if it works, but..... keep in mind these things dependeding on what phone you use to guide you....
screen size
DPI scale
sense??? or not! as settings are different
and other things, also..... when you unlock it make sure its on the home screen
i also believe if you go outside you can see the screen a little bit under the sun, but not completely sure
hope this helps, oh and by the way, if you have a build based on sense go to a sprint store and use an EVO lol, or if u have stock froyo grab a nexus one from a friend and use that (but like i said before, keep in mund the screen size)

yea thats what i was tryin to do. no luck.

I had this problem twice and rejoice, I have a solution!
Simply download "DroidExplorer" for windows.
Boot your phone in android.
Once booted (when your screen turns black), plug in USB, and launch DroidExplorer.
In DroidExplorer, look for the "Screencast" icon (little android icon).
Run that, you will see your screen. Reset brightness to a normal level.
You are saved

aznsHD2 said:
I installed a battery booster app from the market, and it had an option to dim the screen, it was on 11%, well i tried to adjust it, and i guess i went way to far and it turned my screen black, i cant see nothing.
im on the Darkstone build.
is there a way to either delete that app or what, i know the phone works as i feel the vibration from me sliding it to unlock from home screen.
Click to expand...
Click to collapse
When this happens, try shining a bright light on the screen, make sure the device is woken up (i.e. press a hard button) and view your screen from different angles. Even if the backlight is completely off, the LCD display is still active and the graphics elements just about visible.
With this method, you should be able to make enough of your screen to navigate to the brightness settings.
Screencast in Droid Explorer (for your PC) is also a good last measure.
Most apps that control brightness has this problem on HD2, so be careful about going too low in all of them. In Tasker, for example, 30 is the lowest setting that works.
Even the standard screen dimming that occurs a few seconds before screen timeout is not calibrated correctly. In all Android builds/kernels I have tried, the backlight is turned off when it should be just dimmed. Cyanogen(mod) has a setting for the dim level, but the maximum you can use is 26, which still turns off the backlight.
Curiously, sometimes (very seldom) after waking my phone up from standby, the backlight is in a much dimmer state than usual. When sliding the standard brightness from min to max, the actual brightness range varies from barely visible (but still on) to the regular dimmest level. So the device *can* support incredibly dim levels, but I've have found no way of getting into this state predictably. It has happened only 3-4 times over the past 2 months. A reboot fixes it, but I've also gotten out of this state after a locking/unlocking cycle.
So there seems to be several layers to the backlight brightness:
- the actual hardware (which supports much lower brightnesses than we're usually allowed access to)
- the Android API (which probably is the layer turning backlight off below 30, and which occasionally is fooled into using a much dimmer range than usual)
- whatever app providing the GUI (usually showing a range of 0-100% or 0-255).
Does anyone know if there's a reason for the threshold? Is it somehow risky for the LCD display hardware to be very dim?

[Solved] Brightness dims very dark every wake?

Ever since as long as I can remember, my phones brightness will dim to a brightness so dark you just can't see it. Even if you manually set the brightness, once you lock and wake the screen, it's fine then suddenly switches to dark.
I've used multiple ROMs and they all do it. Is it a device issue, or could it be a kernel issue? I've not screwed with kernels so I don't know if it could be it. If it's a device issue, I'll be getting a replacement ASAP.
Any help is appreciated!

Now that I'm able to Google, I realize it's a common problem with the S4.
Sent from my SGH-I337 using Tapatalk 4

Serfma said:
Ever since as long as I can remember, my phones brightness will dim to a brightness so dark you just can't see it. Even if you manually set the brightness, once you lock and wake the screen, it's fine then suddenly switches to dark.
I've used multiple ROMs and they all do it. Is it a device issue, or could it be a kernel issue? I've not screwed with kernels so I don't know if it could be it. If it's a device issue, I'll be getting a replacement ASAP.
Any help is appreciated!
Click to expand...
Click to collapse
The only time I had the screen go dim like you describe is I remember once following a phone call. It goes dark when you put the handset to your ear like it's supposed to, and lights back up when I pull it away from my head. I was stepping out of a truck into the broad daylight when I tried to hang up my phone, I couldn't see the screen very well. The other party ended the call, and my screen timed out while I was squinting at it. I pushed the home button and it lit right back up nice.
You got something going on, and if you tried all those different roms, say... can you nandroid back to stock? Did you try that?
I'd try everything I could on the outside chance of repair instead of replacement. If you get a replacement you might be stuck with that MF3 where you cannot install a custom recovery.

fukenbiker said:
The only time I had the screen go dim like you describe is I remember once following a phone call. It goes dark when you put the handset to your ear like it's supposed to, and lights back up when I pull it away from my head. I was stepping out of a truck into the broad daylight when I tried to hang up my phone, I couldn't see the screen very well. The other party ended the call, and my screen timed out while I was squinting at it. I pushed the home button and it lit right back up nice.
You got something going on, and if you tried all those different roms, say... can you nandroid back to stock? Did you try that?
I'd try everything I could on the outside chance of repair instead of replacement. If you get a replacement you might be stuck with that MF3 where you cannot install a custom recovery.
Click to expand...
Click to collapse
Mf3? Is that something new with the S4s to prevent custom ROMs?
It does not go pitch black. It goes very dim every time I wake the device. If you Google S4 screen dimming it's a wide problem.
Once you wake it, it's fine for 2 seconds and dims quite dark. It is not screen timeout/sleep/etc since I can still see the screen.
Sent from my SGH-I337 using Tapatalk 4

I'm on MDJ and don't get any auto dimming of any sorts. Auto brightness is off, brightness controls about 1/3 brightness (indoors), but Power Saving mode is on with all three options on.

My S4 is MDL. I found out the problem (More than likely) was the Paranoid Android ROM. I was on ver. 3.69 and since switched to CM 10.2 Nightlies, latest as of today, and no screen dimming. I will install my usual apps and use it as normal and if it happens, it's probably an app. However, the only apps I use are ones such as SwiftKey, LightFlow, ASTRO, Chrome, and Dashclock.

I'm on stock MDL. It has only been occurring since I upgraded from MDB 3 days ago, and is a huge PITA because brightness controls are unresponsive during this time - I go into settings to adjust brightness since I have removed all the brightness controls from the notification panel as they've always worked just fine, and turn off auto brightness, scale it all the way to max, and it is still dim as crap.... Only fix I've seen is to reboot, which is obviously not ideal in most situations when I need to wake the device! I'm using STOCK kernel, STOCK ODEXED ROM as well, nothing crazy should be going on to screw with brightness settings being unresponsive either!

KryptosXLayer2 said:
I'm on stock MDL. It has only been occurring since I upgraded from MDB 3 days ago, and is a huge PITA because brightness controls are unresponsive during this time - I go into settings to adjust brightness since I have removed all the brightness controls from the notification panel as they've always worked just fine, and turn off auto brightness, scale it all the way to max, and it is still dim as crap.... Only fix I've seen is to reboot, which is obviously not ideal in most situations when I need to wake the device! I'm using STOCK kernel, STOCK ODEXED ROM as well, nothing crazy should be going on to screw with brightness settings being unresponsive either!
Click to expand...
Click to collapse
Do you by chance use Light Flow?
I solved the problem. I had "lcd_backlight" control flipped on in the settings of Light Flow. It fixed it. To tell if it's an app problem, just factory reset and try, once you boot up, to lock and wake the device to see if it happens. If it doesn't, it's an app problem more than likely, or even a general setting. Troubleshoot for the win!

Serfma said:
Do you by chance use Light Flow?
I solved the problem. I had "lcd_backlight" control flipped on in the settings of Light Flow. It fixed it. To tell if it's an app problem, just factory reset and try, once you boot up, to lock and wake the device to see if it happens. If it doesn't, it's an app problem more than likely, or even a general setting. Troubleshoot for the win!
Click to expand...
Click to collapse
I do use Light Flow, but I don't have either one of the LCD Backlight controls enabled, never have and never will, so I don't know how that could be affecting my phone at all.... That's a good start for some, but not for me, unfortunately! Good catch though
Sent from my Samsung Galaxy S 4 using the XDA app

Serfma said:
Ever since as long as I can remember, my phones brightness will dim to a brightness so dark you just can't see it. Even if you manually set the brightness, once you lock and wake the screen, it's fine then suddenly switches to dark.
I've used multiple ROMs and they all do it. Is it a device issue, or could it be a kernel issue? I've not screwed with kernels so I don't know if it could be it. If it's a device issue, I'll be getting a replacement ASAP.
Any help is appreciated!
Click to expand...
Click to collapse
I had this issue before on my Galaxy S3. I ended up replacing the front glass because of a dead pixel. Come to find out I had a sensor issue and that was causing my brightness auto going to whatever level it wanted.
Perhaps you're experiencing that too. Haven't heard or read of any sensor issues yet with the S4 but you could be the lucky winner!

ZE552KL screen flickering at lowest brightness level

I would take a video of this issue, but I don't have a good enough camera. It's really, really hard to capture unless you have good video recording tech, which I don't have. :crying:
My issue is that, when I set the brightness to its lowest level on my Zenfone 3, the screen starts flickering. This is especially noticeable with white backgrounds. You can tell that the screen is flickering (perhaps refreshing?) rapidly and it makes the phone painful to look at.
Someone actually created a thread about this issue here on XDA a few months ago, with a video showing this issue, but unfortunately, the video doesn't capture the flickering properly. Here: https://forum.xda-developers.com/zenfone-3/help/ze520kl-low-screen-light-level-20-t3603502
How to reproduce:
-Turn auto-brightness off
-Slide brightness bar all the way to the left (AKA to the lowest level)
-Open a white background/grayish background or blank page in Chrome
-Screen starts flickering
It happens across the phone, and intermittently. Sometimes it happens, sometimes it doesn't. In Chrome, in games, whatever. I once thought it could be related to charging the phone, but the screen has flickered on low brightness even when my phone wasn't plugged in, and at 70-80% battery. I might try resetting the phone to see if it's a software defect; I really hope it is.
Turning off hardware overlays in Developer Options does not resolve this issue.
I'm currently on ASUS stock Nougat, unrooted. I can't root right now. I don't have any screen overlays apart from CF.Lumen, which isn't set to come on during the day, when the flickering happens, and I don't use any screen color modes apart from the default settings. I also always have auto-brightness turned off.
Just wondering if anyone else is having this issue. I might try recording it one day.
Thanks.

Update 1: Removed my 64GB SD Card from the phone to see if that made a difference. It didn't. So the flickering isn't related to power management, AFAIK.
Next step is to wipe the phone completely, including its cache partition from stock recovery, and set the phone up as new again. It might be a hardware issue, but my fingers are crossed.

I've had this issue since I got the phone, ZE552KL. Turning off auto brightness fixes it for me, so I have a feeling it has more to do with ASUS' auto brightness algorithms than anything else.

sensi277 said:
I've had this issue since I got the phone, ZE552KL. Turning off auto brightness fixes it for me, so I have a feeling it has more to do with ASUS' auto brightness algorithms than anything else.
Click to expand...
Click to collapse
I always have auto-brightness turned off. I think it might have to do with the ambient light sensor. I've tested it using SMMI and it works just fine. But I wish there was a way to disable it, since I don't need it. I'm kind of disappointed in this phone.
I'm going to try a full reset, and perhaps a custom ROM to see if it's a hardware or software issue.

A5 2016 sometimes won't wake up, screen flashes

Hi,
I have this phone for little over 2 years. For over 1 week now I'm experiencing my phone not being able to wake up when I use the power button/home button. Whenever I push the button, the screen flashes for like 1s blue color, you can also see that the notification panel is blacked out and part of it green and it doesn't wake up. Sometimes it doesn't even flash. It used to take about 10 tries to wake it up but today I couldn't wake it up. I performed soft reset, I couldn't see the booting animation at all but it rebooted, buttons lit up and I was able to get in. It's like the phone is working fine in the background but the screen doesn't light up. I can turn down/up the volume, take a screenshot, get into settings, open apps, write a message but the screen is black. Even my alarm went off this morning but I couldn't dismiss it.
I downloaded an Always On Display app. Although I don't actually see the screensaver when it's locked, it's still on and it's easy to get in beacuse of it.
It all started with the screen flickering on minimum brightness. In February this year I had the screen replaced for the same issue but this time it's worse because of the blacked out screen.
Any ideas what it could be? Faulty display again?
Thank you

tessicorn said:
Hi,
I have this phone for little over 2 years. For over 1 week now I'm experiencing my phone not being able to wake up when I use the power button/home button. Whenever I push the button, the screen flashes for like 1s blue color, you can also see that the notification panel is blacked out and part of it green and it doesn't wake up. Sometimes it doesn't even flash. It used to take about 10 tries to wake it up but today I couldn't wake it up. I performed soft reset, I couldn't see the booting animation at all but it rebooted, buttons lit up and I was able to get in. It's like the phone is working fine in the background but the screen doesn't light up. I can turn down/up the volume, take a screenshot, get into settings, open apps, write a message but the screen is black. Even my alarm went off this morning but I couldn't dismiss it.
I downloaded an Always On Display app. Although I don't actually see the screensaver when it's locked, it's still on and it's easy to get in beacuse of it.
It all started with the screen flickering on minimum brightness. In February this year I had the screen replaced for the same issue but this time it's worse because of the blacked out screen.
Any ideas what it could be? Faulty display again?
Thank you
Click to expand...
Click to collapse
It's over to have this phone for little over 2 years now you should have to change
TIP:
Flash a new stock rom of your phone from sammobile via ODIN.

Sophia.xda said:
It's over to have this phone for little over 2 years now you should have to change
TIP:
Flash a new stock rom of your phone from sammobile via ODIN.
Click to expand...
Click to collapse
That would be great, but I'm not a person that buys new phone every 2 years. I was thinking about it though .
When it comes to flashing. Do you think that would help? I don't want to end up with a black screen unable to set the phone up again. Cause overall it's working great .

Hi, i have the same problem, i'm from Belgium, and I have blinking screen problem and wake up screen problem :s
is it a software issue (nougat???)
before the big update (marshmallow i dont have any problem)
i'm on firmware A510FXXS7CRJ6_A510FLUX7CRJ1_A510FXXU7CRJ6_HOME.tar.md5

Turn screen brightness up abit to stop the blinking of screen. It's an issue of the screen hardware itself at low brightness after wear and tear. As for the hanging issue, maybe it has to do with your AOD app? Try uninstalling the AOD app OR flashing a stock Rom OR custom rom OR factory reset and use your phone at a higher brightness that the screen does not blink and see whether it still persists.

conanDO98 said:
Turn screen brightness up abit to stop the blinking of screen. It's an issue of the screen hardware itself at low brightness after wear and tear. As for the hanging issue, maybe it has to do with your AOD app? Try uninstalling the AOD app OR flashing a stock Rom OR custom rom OR factory reset and use your phone at a higher brightness that the screen does not blink and see whether it still persists.
Click to expand...
Click to collapse
Thanks, because of my past experience with the same problem earlier this year I know about that "solution". Unfortunately, it makes the battery die faster as expected. Which is sad because I used it mainly on low brightness. So it's really not a solution at all.
I got rid of the AOD app because I found out that the phone lights up on 2nd try. AOD didn't work at all. I have to wake it up, put it to sleep and wake it up again which is always successful and the screen lights up. The screen flashes white about 3 times in a row now otherwise it works.
I haven't flashed it yet although I wanted to. But I will see what can I do. Thank you though!

I'm having the exact same issue using LineageOS.

It's already been 2 years, but since this thread is one of the first results on Google, I'll gladly add a solution.
Exact same problem for me, went through two screen repairs under warranty, and it would always come back a year later. No difference between Samsung OS and LineageOS, though I haven't tried rooting it.
Found on Ifixit: this issue is related to the AMOLED screen technology used by Samsung (among others). You can look it up, apparently there is a bad (?) voltage management in low brightness which worsen with time.
I could fix it with the "OLED Saver" application on Play Store. It works around this voltage management and allows you to reduce the brightness without the green flickering.
I still got white flashes after the installation, but not anymore the day after. I could even disable this application without the issue coming back.
I don't know what kind of magic cleanup this app performed, but it really is a (screen) life saver.