A broken internal screen doesn't necessarily require complete device replacement. Fortunately, partial disassembly of the device to access the affected components of the broken internal screen is possible regardless of your level of familiarity with electronic device disassembly and repair. Disconnected cables that result in backlight and video failure are the likely culprits behind the broken screen. You can repair it without any special tools.
Power down the device that has the broken internal screen. Confirm that you disconnected the device from the power outlet.
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Remove the screws from around the screen's bezel. The bezel is the plastic perimeter that surrounds and encases the broken internal screen. Find and remove each, using a Phillips screwdriver. Depending upon the device model you are working with, these screws may be concealed by plastic caps. Pry the caps off with your fingertips or the end of a flathead screwdriver before you attempt to remove the screws.
Pry around the edges of the loose bezel to remove it gently remove from the broken screen. This will reveal the inverter board centered just below the screen's bottom.
Examine the two cables that connect into the inverter board. The inverter cable and the video cable each connects into a separate white connector. These connectors lie on opposite ends of the inverter board. If the general video cable or inverter cable is disconnected from these connectors, general video failure or screen backlight failure can occur, respectively.
Pull up slightly on the affected connector. Take care not to lift up more than a couple millimeters on the connector, otherwise you will break it. Slide the inverter or video cable back into the connector before releasing the connector. It will move back into place and secure the cable, restoring the video functionality or backlight functionality to your broken internal screen.
Replace the bezel and its screws.