If you really think that is a software problem, try to run the device in recovery mode and see if the screen is working before to repair it. You can even reset the device in order to go back to the initial state of the operative system. Try this (same steps for the A8): https://www.youtube.com/watch?v=gujg00lj...

Yes, you have to be root in order to copy the file, in XDA Developers they explain all the process. https://forum.xda-developers.com/galaxy-a8-2018/samsung-galaxy-a8-2018-themes-apps-and-mods/fm-radio-sm-a530w-t3883199 Don’t you have the possibility of use TuneIn or any other app to listen to the radio? Regards.

Hello! I had the same problem some time ago. I tried the typical solution of putting the cellphone in rice and wait but it did not work. The solution of using rubbing alcohol and clean it up with a Q-tip works, but sometimes, the cellphones does not reset the state of wet and it is hard to charge it again, even when is completely dry. I needed to turn off the phone and then connect it when it was on the process on been turned on, then the test is going to be run again. Also, if you want to turn off the notification of wet charging port, you should also delete the data of the USB Settings app, inside of the Apps menu (showing the system apps). Those two solutions helped me to fix the problem. I hope that helps you as well. The A8 is a really good device and this issue is very common but also, very easy to fix.