This issues has been many, same with another device Galaxy Note FE, S9 & S9+ most issues come after updating to Oreo, i have same problem too, i has try searching and trying any sollution on the web, nothing all can't solved, last day so i visit to service center and CS has told me it's 100% hardware issues, i have wait for 2 hour's and done, cos my device under warranty samsung has replace board with new one free of charge.
Wish that help you.