"Finally got this fixed. it sounds like the reason for this is that since the latest update your phone cannot decide whether to use hardware or software back light settings. I managed to make the problem go away by doing this:
Go to settings >> system >> About device.
Find ""Build number"" and click 6 times fast on it.
You will then get the message saying: ""You are now a developer""
Come back to Home Screen, and then go back to Settings >> system >> Now you will see the ""Developer Options""
Now go to Developer options >> Drawing Section or Rendering Section >> Find ""Turn off hardware overlays"" or ""disable hardware overlays"" >> This will force the phone to always use GPU for screen adjustments. no more flickering."
"In my research thus far, the AMOLED screen technology is to blame. When the display circuits get old or damaged, they don't sustain current at low power settings. In LED screens, a back light controls brightness, but AMOLED screens send current to each pixel for brightness control. If the circuit is damaged, or any corrosion has built up inside, this could attenuate the current below the point required to sustain light flow. I see this problem with some LED and CFL lights on motion sensor switches. Just enough current goes through the motion sensor to keep it's circuits active, and that current causes a flicker in the light.
With the screen though, since the problem is only resolved when you increase the brightness just a bit above minimum, it seems anything that lowers the display power (auto brightness for example) will cause it to flicker if this setting gets too low. I also noticed that before the screen locks on timer, it dims to low power for a few seconds and flickers as a result. There are apps that attempt to resolve this by putting a translucent black screen over your desktop and apps. This keeps the power up on the pixels but adds a black overlay, kind of like a screen filter. You can adjust the darkness if you need it to save your eyes when reading in the dark but it doesn't help save power any. They also require a rooted device, which could void warranties. The reason for this I believe is because apps are supposed to operate in a way they don't intrude on each other, and a filter that lays over your screen does in fact alter the output of your display rendering. With the added security concerns of these apps possibly collecting screen shots and sending them to another site, I would avoid this. Best to use a physical screen overlay you can put on or remove as needed as long as it doesn't interfere with your touch screen options.
Ultimately, these devices were meant for replacement every 2 to 3 years so if you're like me and you like to make your investment last, best thing to do is apply any work around you can come up with. A repair shop may be able to wipe the circuit boards down with a solution that clears away corrosion, but it won't repair any weakened pixels. I'm still using a Samsung S4 and only now that I have verified it won't upgrade to the Android 6.0 OS am I considering replacing it within the next year or so."
"I confirm that low temperture is the cause and I can explain why after the factory reset, the problem goes away for a while.
Simply, after doing a factory reset / master reset, the phone gets very warm, that's a normal thing specially when the phone is reinstalling the system apps.
As you can see, when you get your phone warm enough, your problem will vanish / will be reduced untill it gets cold again. When the phone is so cold, the problem gets worse.
I tested this many times and it's 100% true.
Now I think people who understand the hardware stuff will tell you that the connector is loose.
Finally, we are waiting for a fix and untill that, keep your phone warm as possible as you can."
GALAXY S5 SCREEN FLICKERS WHEN BRIGHTNESS IS SET AT CERTAIN LEVEL
Problem: When the screen brightness is lowered to the lowest setting, the lower half of the screen begins to flicker. Raising the brightness a few notches stops the flickering. I have not dropped the phone or exposed it to water – the issue started out of the blue and it’s driving me mad! Please help.
Troubleshooting: Screen flickering issue can be hardware or firmware problem and since there’s not much information here, you have to other option but to rule out the possibility that it’s just a firmware issue (which I really think it is) by performing hard reset. Of course, backup all your important data before doing that as they will be deleted.
Turn off the device.
Press and hold the following three buttons at the same time: Volume Up key, Home key, and Power key.
When the phone vibrates, release the Power key but continue to press and hold the Volume Up key and the Home key.
When the Android System Recovery screen appears, release the Volume Up and Home keys.
Press the Volume down key several times key to highlight ‘wipe data / factory reset.’
Press Power button to select.
Press the Volume down key until ‘Yes — delete all user data’ is highlighted.
Press Power button to select and start the master reset.
When the master reset is complete, ‘Reboot system now’ is highlighted.
Press the Power key to restart the device.
If the hard reset failed, then have a technician check the problem for you."
I had the same issue with my Samsung S5 phone, and it turned out that the Micro SD card was the problem. I too had given up, and started looking for a replacement. I decided to copy the contents of the Micro SD card so that I could transfer the data to the new phone. When I removed the card, I noticed that the phone was functioning normally. I also received an error message when I inserted the SD card into my computer, that the SD card had errors that needed fixed. I fixed the errors, copied the files to the hard drive on my computer, and then re-formatted the SD card, and my phone is like new. The screen no longer flickers. This appears to be a fairly common problem with the Samsung phones that use Micro SD cards. My first suggestion is to remove the card if you have one, since it may be the cause of your flickering screen.
