Screen flickers, stops after brightness change
From my experience this could either point to a defective inverter board or a simple short-circuit on the cable that runs from the logic board to the display through the display hinge. I´d suggest visiting your nearest Apple Reseller / Apple Store or (if you´re technically experienced) trying the repair yourself (a new Inverter Board will set you back around 50$, but the do-it-yourself-repair is really not that easy).