Black screen but indicator works

Common issue in the S6 and S7 where their screens could stop working out of nowhere. You’ll need to get the screen replaced and thankfully they have come down in price over the years. If you’re going to fix the screen, I advise you get the charge port replaced while you have it apart. Micro USB has a tendency to fail as well on these devices and because the buttons on either side of the home button are attached to the charge port, you need to break the screen to replace the port.