Led lamp is always on

Hey! For several months my rear lamp started to be on always, i tried to restore the ihpone, tried several of different stuffs. The battery was always empty.

Suddenly it stopped, and i was a happy man again.

But, yesterday when i changed my lcd screen on my iPhone, the lamp started again when i started up the iPhone. Why is this? Anything wrong inside?

Need answers before my battery is burned.

Peace. Toby