Unfortunately, only fix for this problem is flashing back to official firmware, but if that isn't fixing your problem, then it is advised that you bring it to repair shop before your device gets damaged any further.
This seems like an hardware problem. Don't try to fix it urself as that may damage your device even further. Best course of action here would be to bring it to the repair shop (warranty or no warranty).
That's sad to hear, but the only way to fix this problem is through odin flash. However, more often than not, that doesn't fix the issue either. Samsung really needs to step up their game in this regard, unfixable issues are incredibly annoying