tldr; Turning auto brightness off and setting brightness to the lowest might work.
I have been using the Exynos model for past two years. About a month ago or so the device first exhibited screen flickering issue all of a sudden. Green bars, black screen area, sort of animated and laggy. For the time being, only immediate lock-unlock attempts were causing the screen flickering (meaning, when I unlocked immediately after locking the device, the screen was causing trouble). I left it as it was and just kept avoiding immediate unlocking. Anyhow, after maybe a couple of weeks, out of nowhere the screen appeared to be flickering permanently and the device was rendered totally unusable. I tried doing some troubleshooting, factory reset, odin flash, etc. and none of them worked. Could not visit a service center in this lockdown situation.
Later, I figured that in my case, the screen is working at a very low brightness and partially working at full brightness but not working at all in between. It's just 90% black, 10% green and such. For about a week, I have been using it at a low (i.e. 5% to 10%) brightness. Left the auto brightness, always on display, and screen-on iris recognition settings turned off. I use Bixby or Google Assistant to set the brightness if I can't see the screen. With these setup, it's working for now. As of the software, I am on the latest firmware (May 2020 security patch).
From my observation, the issue had something to do with heating. I am not certain but I feel like the issue occurs more frequently if the device is used for prolonged period and heated up due to gaming or mobile data usage. I would suggest anyone who is stuck during this time before you can repair, should your device work at a low brightness then clean up the phone, get rid of unnecessary apps, games and reduce/avoid long usage that cause heating. Also leave the medium power saving mode on as it limits the CPU usage which supposedly help reducing the heating as well. Do not use night mode, gray wallpapers, etc. Use light or colorful backgrounds, apps, etc.
Thanks. Stay home and safe.
I finally found a usable solution / workaround to the Green tint / flickering issue, that is:
1. Download PWMFree from the XDA thread. This is the current working link
- Until now I didn't want to install it, but after analyzing the .apk file, I found that it is safe, requiring no permissions besides Accessibility, which is required for it to adjust the screens brightness.
2. Check/verify it!
- Option 1: upload it to VirusTotal, check the results! In the Details page, the file's first submission is: 2019-05-06 21:02:03 UTC
- Option 2: only check it's SHA-256 hash, it has to be: 660476a8415b6f950b94b978a7e0f3279a8309fc538cc7c302fef786a009098e
- Note that VirusTotal also display the uploaded file's hash with a couple of algos, including SHA-256
3. Install it on your phone
- Doing it (safely) is beyond the scope of this post, I installed it with adb, but it should be possible from the phone itself if you enable installing .apk files (e.g. enabling installation from untrusted sources, etc.) - if you are not sure, please take the time to read about this (or ask someone to help), and only install .apk files that you absolutely trust!
4. When I first started PWMFree, it directly opened my phone's Accessibility settings page, where PWMFree's Accessiblity service has to be set to "On". It will give you a big warning that this enables screen content reading, etc - since the app's purpose is to modify the screen with an overlay (to reduce the screen's brightness without using PWM) this is really needed - and remember - the app has no other permissions besides this, so it can't upload your data anywhere, etc.
5. Set AOD (Always On Display) to be either "Tap to show" or "Always enabled"
Update: "Always enabled" would save the many taps we had to do until now without PWMFree and with "Tap to show" AOD mode. With PWMFree the "always enabled" mode might be actually usable and useful, since thanks to PWMFree the phone's screen might be always readable, even when it's greenish - which only occurs when you unlock the phone quickly after locking, while AOD is still loading. Otherwise (most of the time) the screen can be correct.
Update: after a couple of days I reverted to "Tap to show", as with "Always enabled" the screen was still flickering sometimes.
The screen (especially some gradients) look a bit strange at first with PWMFree, but the very big (and eye-saving) advantage of this solution is that the screen no longer flickers (PWM flickering - check it by pointing another phone's camera to the screen - no moving lines this way)! Now I regret that I have not applied PWMfree before - would probably have saved some eyestrain.
That's it. The phone is usable again, saving some precious mineral resources and of course time (setting up everything on a new phone) and money. I was almost at the point of buying a new phone, since Samsung offered no real help.
Exactly the same problem. When I turn it on, I have to put the phone in the fridge and eventually the password screen appears. I then power off, have "always on" on, "adaptive brightness"off, double tap screen, then open with fingerprint. If I use fingerprint only, the screen is only visible with the brightness at maximum or 1-10%. Brightness at 100% is a difficult green hue with pics looking fuzzy. You can slide screen brightness bar to see where it turns off, just don't release your finger until the screen is back on. In any case I press power off button, double tap screen, then fingerprint unlock for normal screen. I can't make phonecalls without the screen going black, which is rubbish.
Very nice to read the thread solutions over 2 years, but sad it still hasn't been fixed.
For those who are still reading this thread, I wonder about the heating we observed. We installed a Samsung EVO memory card. Do u also have a memory card installed? Just wondering if having memory card adds heat and eventually breaks the screen. Or if the battery bloated causes the screen to bend and break? I went to Samsung service center again for this 2nd occurrence and requested a detailed explanation why this happened for the 2nd time considering I gave this phone to my mother after the 1st screen replacement and all she does is facebook and YouTube. So far, they are telling me to pay $200 for the screen replacement in order for them to investigate further. And this is how I ended here, self researching instead. Now having doubts if I will still proceed with 2nd screen replacement after reading all of your replies
everything was going well with my s9 ,But one day suddenly while i was watching a YouTube video with loudspeaker (and also the phone was with excess heat due to loudspeaker and data usage),i experienced this small strip line issue all over the display.But at lowest brightness level the issue was fixed up to some extent.Now the issue is completely vanished after the heat was dissipated. But don't know when will this occurs again. I took following remedial measures to be in the safe side from possible future occurrence of this issue again.
do every possible thing to reduce the heat generation. If there are issues with battery, Resolve those problems also.