Darkness with in the self can be a metaphor for both ignorance and negative emotions.
It is important to remember when using darkness as a metaphor for the parts of ourselves that we don’t know and don’t understand; that while yes the darkness can be banished by the turning of a light, sometime the darkness conceals real horrors within ourselves, which do need to be fought. Shame, fear, anger, the scars of old trauma, all collect with in the darkness. In these things, the darkness exists to protect us that which we are not yet able to face. Therefore, if the light will not come on, and you must ‘fight’ the darkness, it is probably because the part of you that you can not see knows of the horrors and is not yet ready to face them. Trying to force the light on, force yourself to face the horrors, is not bravery, and waiting is not weakness. It is wisdom to know that before you can climb Everest, you need to be able to climb a hill without exhausting yourself. Mental and emotional training are in this the same as physical.
Trust yourself to know when you are ready to face your darkness. And when the time comes to see the truth of what it hides, do not flinch or hestitate. Face the thing your darkness has hidden. You will know what to do with it, if you are true to yourself.