Iphone 5s screen turned black still hear siri when i click home button

Recently last week i sent my iphone for a repair because my screen wasnt working when ever i try to glide my fingers to move my screen anyways today i just got my iphone back and it was working fine like any normal iphone ...so i was on it for like 10 minutes then my screen went black i couldnt see anything but a light black light and i still heard siri i try holdin the lock button and the home button at the same time but i didnt see the apple logo i also saw my screen shut off and turned back on but still couldnt get it to work