This is a fairly common issue. Please excuse my technical speaking but there is no other way to get this across. There is a chip on your logic board that supplies power to your screen. This is most likely what went bad. There are 25 connections to the board. This chip needs to monitor the voltage is it outputing to the screen or it will not work. There is a connection that commonly burns when this chip fails called Feedback. Without this connection the chip will not know how much voltage to output so it will shut off. The technician most likely did not run a wire to this connection under the chip and hence after a few days of use it failed. Still a fixable issue just needs to go back.