The “black screen of death” is pretty easy to figure out: your device’s screen appears to be either completely off or is blank but illuminated by the backlight. In either case, you may notice the device’s notification LEDs still working or blinking, which may indicate a problem with the display hardware rather than the battery or charging port. If the notification LEDs aren’t illuminated and you can’t hear any sounds from the device, it may be completely powered off and the issue may be related to the charging system.
You may notice some symptoms before your screen goes black, including the device restarting on its own, freezing, or just being generally more buggy than usual. If these things are what you experiences before the screen stopped working, there is a solid chance it’s “the black screen of death.” If the device began acting unusual before the screen went dark, it’s possible the issue could be due to a buggy app, meaning booting into safe mode may be the right solution.