My Apple TV light flashes continuously

For Apple TV (4th generation or earlier) [models prior to the 4K models], users may be able to re-install the system software themselves, by restoring through a computer. Restore your Apple TV - Apple Support

Please unplug it from it's power source for 2-3 minutes then plug it back in. If the problem continues that means TV OS was corrupted and you need to take it to your local Apple Authorized Service Provider to have it worked on. You can refer to Reset or restore your Apple TV to its factory settings and you need it please use Apple Authorized Service Provider Locator (AASP) & Genius Appointment