Screen flickering on low battery or dimm

Well, that's the issue. The screen backlight flickers like crazy upon dimming before turning the screen off, or when the device is on low battery (say 5%), or simply when the brightness setting is below 10% (I think. Meaning, low). I've read a loooot of BS (room temperature, background apps, cache partition, SD card, blabla), all circumstantial so far but no SPECIFIC explanation/fix as to why or how this happens, and/or the correct way to "fix" it, if can be done, or what part to look up to repair/replace. It is very frustrating to browse so much guessing without a clear solution. Please?