either the connection is loose on the display cable, or the screen could be broken also the display brightens could be turned all the way down depending on the model of laptop some have a dedicated button to turn the display on/off
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either the connection is loose on the display cable, or the screen could be broken also the display brightens could be turned all the way down depending on the model of laptop some have a dedicated button to turn the display on/off another thing I would try is removing the battery and having plugged in to the wall sometime a bad battery will do it
either the connection is loose on the display cable, or the screen could be broken also the display brightens could be turned all the way down depending on the model of laptop some have a dedicated button to turn the display on/off