This is the 11433rd most frequent Korean word.
꺼지지
"꺼지지" means "does not go out" or "does not extinguish."
Here, '꺼지지' means 'unextinguishable,' describing the flame that doesn't go out.
사랑은 꺼지지 않는 불꽃처럼 계속 타오릅니다.
Love burns like an unextinguishable flame.
Here, '꺼지지' means 'turned off,' as in whether the phone's screen powered down or not.
휴대폰 배터리가 다 닳아서 화면이 꺼지지 않았어요.
The phone's battery drained completely, so the screen didn't turn off.
In this context, '꺼지지' refers to the fireworks not ceasing or extinguishing.